Hi Alexander,
Thanks for the question...

One of the areas of concentration at Yamaha is the development and production of cutting edge Effect processing for audio. You find these in the Digital Mixers as well as the synthesizers. The Rev-X was introduced in the SPX2000 (2003) and was implemented in the 2007 flagship workstation synthesizer line the Motif XS in 2007 (read about it here) Naturally, if it was in the Motif XF (2010) and later the MOXF (2013) - they moved those Effects into the MONTAGE/MODX engine.

Effects in the MONTAGE and MODX are culled from processors including the SPX2000, and as far back as SPX90. And include many of the VCM (Virtual Circuitry Modeling) effects, that adorn Yamaha's Digital Mixers. These are indeed the same Effects... it's a great story but among our engineers are guys that discovered a completely new form of synthesis on the way to working on an effect processor chip! The synth engine sort of developed as a kind of side benefit of research on an effect... And to complete the circle of strangeness, the whole digital mixer concept grew out of creating a digital processing signal path for the old DX FM synthesis system (TX816). Back them synths did not have onboard effects of any kind... the DMP7 was initially designed to be the automated mixer for the TX816 system... each TF1 module was a DX7 and had its own channel on the DMP7 mixer... and when you sent a program change from your KX88 (Controller) it recalled eight DX7 sounds and sent a program change to your DMP7 (those mixer program changes were called "Scenes" )... Circle of life... This way each synth program could have its own customized effects, EQ, Volume, pan, etc., etc, all the things that are built-in to the current day synth engine... including Scene recalls. (But back in the day circa 1987, the digital mixer was an external device for your KX88 controller > QX1 sequencer > TX816 tone generator > DMP7 digital mixer system. Deluxe! Talk about cutting edge...

Extra Credit:
Yamaha Digital Mixers

New Effects are added to the MONTAGE/MODX via firmware Updates... always check in for these firmware Updates - We try to make a big deal out of them but still some users miss out.

Ok, Bad Mister. Thank you for detailed answer. In this case I have another question about MODX/Montage FX architecture. Is it possible use MODX's Fx as FX insert in the DAW?
I guess, probably I can't do that, right?

MODX's insertion, system, and master effects can be applied to the A/D inputs. The A/D input can source from the MODX digital inputs (USB). And the result can be sent to MODX's digital outputs. In this manner, one could send audio from the DAW through MODX via MODX's A/D inputs - which have programmed effects on them - then DAW receive the result from MODX's output.

This requires the MODX hardware to be actively configured and part of the setup. There's not a virtual instrument version of MODX that you can instantiate solely as a plugin. I'm not sure if this is anything close to what you were looking for (a pure plugin solution) - but IF it is, there are some options:

https://www.steinberg.net/en/shop/vst/yamaha_vintage_plug_in_collection.html
Note: I stopped here in my search. You could likely search and find more offerings out there.

In this case Yamaha SPX2000 better variant instead of MODX, I guess. Because I can use this hardware processor as VST plugin. Honestly, I don't know how much tracks I can use simultaneously, but quality of reverb and delay really impressive.

Yes, to some degree, you can. Because the MODX is both an audio interface, MIDI interface and a killer synth, why not?
As an audio interface, it is considered a 10-in/4-out Audio Interface. That means the computer will see it as 10 Inputs coming In, and the computer will be able to send 2 Stereo Outputs back to the MODX.

The 10-ins are the 10 USB buses from the MODX. Main L&R, plus USB1-8.
The 4-outs are the two Stereo Outs from the computer back to the MODX. The first pair go directly to the Main L&R Outputs of the MODX. The second pair, Digital L&R Outputs, return to the internal mixer of the MODX (which where you can process them with MODX Effects).

When you want to use it as an effect processor, this may impact what else you can do with it at the same time. It is not designed to be simultaneously the killer synth and a full fledged Effect processor for your DAW tracks, but in a workflow with a DAW you can certainly find a way to route signal to the MODX on the Stereo Digital Return bus, where you can process the signal with MODX's boutique grade effects and route it back to your DAW for recording. You would create an Audio track to record the "wet" signal -- i.e., the return from the MODX Effect.

You would setup a SEND from the DAW to MODX - that would be an additional stereo Output. "Digital L" and "Digital R"

Signal sent to the MODX via the "Digital L/R" will arrive in the MODX internal engine as the "DIGITAL IN"
From the HOME screen
Press [EDIT]
touch "Audio In"
The top half of this screen is the "Analog In" (A/D In). The bottom half is the "Digital In" and represents signal coming from the computer on this second pair of USB buses from the computer to the MODX.

You have "Input Mode" (Stereo, L Mono, R Mono, L+R Mono), "Volume", "Pan".
If you assign the signal to the Main L&R you have access to "Reverb Send", "Variation Send", and "Dry Level".
And finally "Output Select" which is the bus on which it returns to the DAW for recording... The Effect Return.

You cannot use the USB 1-8 Outputs because you will not be able to apply any MODX Effects to those bus Outputs. If you assign the "Digital In" signal to a USB bus Output, 1-8, then this would bypass the System Effects (Rev, Var), Master Effects, and Master EQ. Not what you want.

If you wish to use any of MODX Effects you can set them up either in the Reverb, Variation or Master Effect processor. In a case where you are using the MODX as an external Effect processor for a DAW, you would like set up a Send from the DAW to the MODX "Digital L/R" ... and you would use the Output Select = "Main L&R" to then return the Effects from MODX to a Stereo Track in the DAW. This track would record the Effect Return.

Obviously, if isolation is what you want - you would work with one input at a time.
If you want to set it up as a "pool" type effect - where everything you send in will be processed and send back as a stereo return (typical Send/Return scenario) this can be done. This would be how you could set the MODX as a hardware external Reverb Chamber - you could process your mix down through the MODX's "HD Hall".

Hope you see what I'm saying. No you cannot also use the MODX as a Synth... I say that because, likely when printing effects you want to be able to control what is fed to the Effect and what gets returned in the "wet" signal.

Hope that helps. BTW - it makes a killer processor.

Wow! Bad Mister! Thank you for detailed answer. I'll follow your instructions and try to do something best for my songs. Thank you again!