Evolving from a avr to an av processor. Benefit?

I don't think the AVR vs. AVP is a big deal so much as who is doing the processing.

Do listen to the Anthems. I like the sound a lot better than Marantz.

I currently run a mixed HT/2-ch system.  I have a Luxman integrated which lets me bypass (i.e. split) the preamp and let the Anthem AVP take over.  I won't let go of my Luxman for anything, so this is the complicated compromise I've done.  If I had an AVR, I'd do the same and eliminate my 3 extra amp channels.

My personal, preference is Mac, I like um. I don’t use all the latest and greatest when it comes to HT, I use a MX 120 and 121. I prefer the former though it’s not the best HT. I’ve found the play through on Mac let’s just about any HT/AV/whatever you want to call it, work VERY well with the added benefit of GREAT stereo sound through the MX120. The 121 is far better HT wise, but that 120 is a real jewel when it comes to stereo sound.

BTW, that’s not just "I like mac talk".. I have over 30 pieces of mac vintage and new, gear. The C2500 is a nice piece with a little work too, again most Macs have "play through" AND dual phono stage, some with MM and MC (with) gain selections.. Your current HT setup might be just fine. You want to improve the Stereo listening experience, the HT or BOTH?

What I'm suggesting is really the best of all worlds, FOR THE MONEY. 
If you look you can find a GREAT MX120 for under 2000.00 and still have great HT in another already owned piece.  I found a MX120 for 795.00 or something close with shipping and Mac shipping boxes too boot. Corner of the front glass had a crack.  In pics you had to really look.  I found the glass for 190.00 NEW. 

Just a though

Regards..

Is 2-channel or surround music important to you, or is this just home theater?