Yup - it'll drive the Diamond's just fine.
How will it compare to the old amp? Who knows, the amps are years and years apart so no one will have a sonic memory to compare. The numerous DSP / audio options on the Yamaha can allow you to tweak the sonic signature easily.
Don't buy into the 'this amp sounds brighter / warmer' by default.
I'd pull the trigger.
Press the 'option' button and you'll find it there.
Check your calibration of the sub and make sure it hasn't been turned down during the YPAO setup.
However, if bass seems weak in the subwoofer department then the very first place you should be looking is its room placement.
Having said that... you'll also want to double check the bass crossover on the subwoofer and in the amplifier menu.
I guess its a bit late, but you could still use the denon for 3d if you bought one of these (or similar).
I own one of these. About $30-40 NZD delivered. I use it because I don't like to pass the video signal through the AVR.
Basically you go from source -> splitter. Then the splitter plugs directly into the 3D display AND the AVR.
HTPC / Home automation (home assistant) enthusiast.