The Tyros5 comes in 61 and 76 synth action keys, with the exact same KEYBED and action as the Motif XF6 and XF7, respectively. If you prefer a piano weighted action, then 61 and 76 key synth actions would not feel right, for you.
I cannot speak about the Vienna Symphonic Library of which you speak, because I am not familiar with it nor any of its features. Sorry.

I do however, recall our discussion, and wonder if you and I are talking about the same thing... The "Ensemble Voice" found on the Tyros5 is described below:

Ensemble Voice is an amazing new feature that reproduces true "divisi" playing in a section. In the past, a Voice like Brass Quartet would use a sample of four players, which sounded great. However, if you played two notes you'd get eight players, which could sound great but isn't the most realistic. Tyros5 Ensemble Voices always get the same number of players because Tyros5 has the musical knowledge of a professional music arranger. Play two notes with a Brass Quartet Ensemble Voice, and Tyros5 will send the trumpets to the top notes and the trombones to the lower notes; it's an incredibly realistic sound. Ensemble Voices also utilize parameters which enliven the performance to reproduce the subtle variations in timing heard in a real ensemble. This provides an authentic sound that sounds as if a group of actual performers were playing and allows you to enjoy playing like an instrumental quartet with ease.

The key thing here is this all takes place in real time, you can actually perform with the Ensemble Voices (with some practice) and can select the type of algorithm applied. If you are not adept at limiting your playing to just four notes, you can use the Tyros5's chord intelligence to do the heavy lifting for you... Your left hand chords will instruct the "ensemble" while you play single finger in your right hand! Check out how Martin Harris makes this happen in the video, brilliantly.

There are about two dozen Key Assign Types that determine the movement of the inner voices when working quartet music. You should download the Tyros5 Reference Manual and read through what Yamaha is referring to when talking about "Ensemble Voices" (as I recall there are 8 such Ensemble Voice combinations). The big deal is real time performance and control, it's an Arranger Workstation, and real time is a key mandate of the instrument.

Please visit this site (link provided below) and see an excellent explanation and demo of the Yamaha "Ensemble Voice" concept. Look on the Audio & Video tab, the entire video is cool but at 18:30 they get into the ENSEMBLE VOICE and how it works. I believe you will discover a difference, at least you will understand better what I was talking about in our discussion of realtime ensemble playing.

Again, I do not know the library you mention ... Or what it is capable of... You will need to make that comparison.
And as to your question about can it be used in a Motif XF, well that's easy, no.
From all I've read on their website it requires a computer to work.

Here's the link:
Go to the "Audio & Video" tab, Tyros5 Webcast

Thank you for responding
Yes , I'm doing everything in real time in Vienna as well ,that's most important for me. I'm using their "vienna instrumens pro " player as a plug in in cubase. It does marvelous things. So I have now motif with VST ediotr via Fire wire and Vienna with their player and works like magic for me together :). You can see how it works here , just in case you were curious : http://youtu.be/A4zwfY72ILA
I wanted to ask you what is the good way of recording performances from motif (with VST edito) directly into cubase ?
And after I recorded performance in cubase is there a way to split the instruments of performance into separate midi tracks?

I wanted to ask you what is the good way of recording performances from motif (with VST edito) directly into cubase ?

The best way to record a PERFORMANCE (using the word in caps denotes the "Mode" - hopefully that is what you are referring to...) is to record the four PARTS to the XF's internal Sequencer, using the Direct Performance Record feature, then transfer the data to Cubase in a separate operation.
Recording the data as MIDI to a DAW like Cubase is incredibly complex because, DAW are designed (mainly) to record one Track at a time... Recording an XF Performance can involve as many as four Tracks, some played directly by YOU, others played by an arpeggiator. Unfortunately the to the computer, it has no idea what YOU are playing and what each of the Arpeggiators is playing. The XF has an advantage because internally the signals travel a different path, so it does know. This feature is called Direct Performance Record and it is designed to record, separate and copy the Parts from Performance mode to either a Song or Pattern. And it does all the heavy lifting for you automatically.

And after I recorded performance in cubase is there a way to split the instruments of performance into separate midi tracks?

Use Direct Performance Record and it is done for you automatically.

That all said, recording the Performance as Audio to Cubase is straight forward and easy. If you have the FW16E installed you can even record each Part to its own Audio Track.
You should consider this option, because not only is it easy, but unless you are going to Edit the MIDI data, there is no reason to hassle with all it takes to get this done. Do you have plans on editing the MIDI data?

The link below will explain how Direct Performance Record will work: See specifically the Section heading "Direct Performance Record"

XF Performance Mode

You would opt to direct the record towards an empty XF SONG location. Then you can have Store your data data to internal memory, Save an ALL data file... And open that file with Cubase's IMPORT > Motif XF Song feature.

Import Motif XF Song

I read the link, thank you.
So this is what I did,while my motif was connected vie fire wire with cubase with opened new project trough cubase templet "motif xf8 VST editor"
1. I have recorded performance with 4 intruments in it into motif sequencer
2.I anabled record in first 4 tracks in cubase that are automatically corresponding with first four tracks in VST editor and motif.
3.i pressed record in cubase and pressed play on motif.
4. The performance recorded with each instrument on a separate track.
So this way I skiped that step with recording from motif to usb and then importing motif song to cubase.that's exactly what I wanted 🙂
And actually I CAN change midi data in each track of that performance. I double click on track and all the midi data is there for that single instrument.
I can also copy the midi of any of the 4 tracks of that performance and assign it to any other instrument I wish from different sound libraries and so on....
That's really awesome ! I only was a little confused if it recorded melody I was playing with the right hand because at some point it was playing back just drums then i did something , don't remember what 😀 and it was playing 4 tracks.......
How do I take all that project now and change it to permanent data, I just record everything as audio or one track???

How do I take all that project now and change it to permanent data, I just record everything as audio or one track???

Sorry, I don't know what you mean.
I don't know what you did, you did not follow any of what I suggested. If you have successful got, as you say "exactly what I wanted". Good!
I cannot begin to guess what you've actually done. The TEMPLATE you used made assignments for you - if they are exactly what you want, then fine.

Are you happy with your result?