Hi Erik,
Welcome to YamahaSynth!

Yes, the Reface CS is unique, it does share some things from previous Yamaha products, but is a unique product. This is the first CS based on a virtual analog engine. Many folks consider the AN1x as a part of the CS-series, but it wasn't in name but in spirit perhaps. The Reface CS is based on an Analog Physical Modeling engine, similar to the AN1x. But the implementation of the technology is entirely different...

As you noted not all Yamaha CS were same, varied indeed, some were analog, some were sample-based synthesizers. CS was short for "Control Synthesizer". Folks who are caught up in looking back are going to miss what's different about the Reface CS...

The Oscillator section of the Reface CS lets you select 5 different tone engine sources:

Sawtooth-MultiSaw
Square-Pulse
Oscillator Sync
Ring Modulation
FM

Sawtooth waveforms are bright and buzzy, they contain all harmonics.
Square waveforms are hollow sounding and contain only the odd harmonics... The square is a 50/50 case of the Pulse family. The narrower the pulse, the more nasal the tone as certain harmonics are missing.

The TEXTURE and MOD parameters that are apart of the OSCILLATOR section and are a key to working with this engine. If you are new to programming you will approach these parameters with your ears, if you are an experienced programmer you will understand that what "Texture" and "Mod" do is different for each OSC Type.

You will also discover that the LFO can be assigned to modify the Oscillator in specific ways according to the selected OSC wave.

For example, if you select the Sawtooth engine...
Raising the TEXTURE slider adds a Sub Oscillator
While MOD turn the Sawtooth into a MultiSaw
If you set the LFO to modify the OSC it will vary the pitch of main Oscillator but not the sub OSC.

If you select the Square engine...
Raising the TEXTURE slider tunes the pitch of OSC 2
While MOD change the Pulse Width
If you set the LFO to modify the OSC it will automate Pulse Width Modulation

If you select the Oscillator Sync engine...
OSC 2 is sync'd to OSC 1
TEXTURE changes the pitch of OSC 2 causing the shape of the tone to change and to remain sync'd OSC 2 is forced to alter its cycle - classic analog sound.
MOD changes the range that OSC 2 can be varied
If you set the LFO to modify OSC it will automate the pitch of OSC 2

If you select the Ring Modulation engine...
The sum and difference of the two OSC are the tone source
TEXTURE changes the pitch of OSC 1
MOD changes the pitch of OSC 2
If you set the LFO to OSC it will modulate OSC 2

If you select FM...
Sine wave source
TEXTURE applies the modulator (increase in output level of the modulator)
MOD changes the pitch of the modulator
If you set LFO to OSC it will modify the application of modulator

The amazing variety of sounds you can make from just these three parameters interacting is immense.

Thanks for long reply but I think you misunderstood my question a bit. I am definetly interested in what is new in this synth and I dont expect it to be an exact remake but it seems like the red thread in this synth-series is that they are inspired by older products. But the fact that the new cs-synth has some different waveforms and LFO etc doesnt seems like a big connection to the earlier synths, i mean it is kind of standard things in synths even if this synth has its own take on it. But when I listen to some of the youtubeclips I can hear a connection in the types of sounds it makes. Even if the cs-series is varied it has a certain personality. It sounds more like the older cs synths than it sounds like a typical moog or a roland juno for example and I mean this in a good way. Recent years there has come some software-synths that emulates old classics so I wondered if you had used similar methods to capture some character from the older cs-synths. But maby not? Or maby its a secret. Anyway, Im looking forward to try it out when it comes out.

I'll take a stab:

A number of things contributed to the unique sound of Yamaha synthesizers. One was the "snappy" behavior of the envelope generators. Another was the use of a 12db/octave filter (similar, but not identical to Oberheim). This filter accounts for the aggressive "screaming/singing" quality of some patches. I've also noticed that pulse-wave-modulation has a different character to it on Yamaha synths than others ... it can produce these very musical reed-like "buzzy" tones which are very useful and sweet sounding.