Actually, if you're NOT using the amp section in the Yamaha, you'll might find the sound difference between the Rotel and Yamie NEGLIGABLE! Then, it gets down to features, EQ', switching and upscaling, etc.
I've had very good success over the years in some systems using the Yamaha as a pre/pro. However, better DSP and EQ technology is out there to do even more with the sound, acoustics, etc. So consider. Most rooms NEED some room correction! (as most people don't have heavily acoustically engineered rooms). In this case, the Parametric in the Yamaha will be at least very helpful for bass peaks in the room, to even out the response, and increase dynamic range and accuracy.
I hear the RXV861 is supposed to be a descent sounding piece. Perhaps even better, most likely, with a better amp! But I've not heard that piece, just hear-say. Ya might check it out. Otherwise, Why not look at the Integra pre/pro as an option? Got all the latest and greatest, including Audyssey MULTEQ.
At the very least, you can go down to your local AV store and by the Yamaha, and try it out! Don't like it? Then just return it!!! Problem solved , there.
Good luck