I have the 1095 and bought it over the 1075 because I plan on buying some power hungry B&W speakers. Unless you plan on driving power hungry speakers now or in the future or play music or movies at incredibly loud volumes levels. the 1075 shoud do fine.
So, 1095 won't bring out more details at same volume level compared to 1075? It's just matter of one sounding louder? Also, all B&W speakers seem to have 88+DB sensitivity, which isn't quite power hungry to me...
Bowers & Wilkins are usually fairly easy to drive, even the Nautilus series. The one thing that is important though with the N series is that you must get a stable amp, as their impedence covers a broad range. Rated at 8 ohms, they dip as low as 3 ohms, and that's a wide swing.
As far as the two amps? I'm sure either one would be a very nice addition to your system.
Anytime you make any changes to your system you should re-calibrate the levels on all your channels. This would take care of any differences in volume. Rotel is very conservative in rating their amps so I don't see you having trouble!
That is exactly what I have done. I now have the Rotel RB-991 (2x200w) powering my fronts and the 1075 powering the centre and surrounds. I do not have a problem with balancing the two. You simply need to recalibrate channel levels. Another thing to consider is that the volume level does not increase in direct relation to the added wattage. What you are getting is an amp better equipped to handle power hungry speakers particularly during peak loads. For me, it was a way of striking a balance between HT and 2-ch music listening.
I have the Rotel 1095 and what I find as the main difference between the Rotel and my Yamaha RXV1000 is that if you are running full range speakers set on large, you have better bass. If you are running all your speakers on small and having your sub carry everything from approximately 90 hz on down, having a more powerful amp doesn't seem to help.