The Synclavier V really sounds good (didn't see the whole V Collection -- would have done that). I use mostly analog synths, and this complements them very well. It's really beautiful - I haven't been so excited about a software synth before.
Just to credit where the credit is due: the Arturia Synclavier is NOT a "soft synth", i.e. it's not a "software model" of something existing "physically" before. The Arturia Synclavier
IS the Synclavier - the original instrument. The Arturia version is a faithful digital clone of the equally digital original, down to preserving certain imperfections to maintain the integrity of the original presets.
For example, you may have noticed that the amplitude envelopes do not always reflect the sound
perfectly along the time axis. This happens if you click and drag an envelope peak - it will likely go very slightly out of sync with respect to the other envelopes, even if your drag motion was straight up. From what I hear this was present in the original (it's not a bug) due to hardware constraints at the time.