I had 800s (yrs very long time ago and a recent 801 model) and I still have the Vs.
The Vs create a wide and deep soundstage behind the spkrs. They are difficult to place correctly in the room but they are indeed adjustable and, at the end of the day, reasonably user-friendly.
They will not offer the fast-in-your-face sound of the 800; OTOH the Vs' frequency response is slightly more extended than the 800, esp in the bass. They are difficult to drive well, perhaps less so than yr present 800s, so you are used to that.
You will probably find that the sound is less sharp, or harsh if you will, than the 800: the Genesis use a pseudo-ribbon tweet (planar) which is the reason for this. However there is no actual loss of information.
The trick with both speakers is to play loud, as you do not get many dynamics with either, esp with the V unless you play @ around 85dB. However, the V will sound better in low spl than the 800. What they Gen V will NOT manage is very high spl: I'd say around 100dB is their millisecond max; the 800 go louder.
Reliability: no problem as long as you use adequate amplification. Some users reported problems with blown tweeters, but most of these cases were due to insufficient amplification power. I never had problems with mine (1996 model!!!).
OK, here is an opinion: the Vs are slightly better speakers because they are more complete -- in a nutshell, the symphony orch will be better reproduced by the Vs than the 800 matrix. But that's as far as this goes. The 800 are just as legendary and justly so.
One small point: 3900 euro seems a tad high for these; 3.3-3.5k would be more like it, IMO.
