X6500h or x4300h.. Please help me pick

OK so, I had the 4300h and was going to get it again as I am setting up my HT room again.
I will have to get a used Denon 3803 or similar amp to drive my mains and use the other 4300h amps to drive my other speakers as I run a 7.2.4 atmos system.
I also have 3 subs and a jvc projector.
It seems even used prices for the 4300h are high.
I started thinking.. What if I get the 6500h instead?
Then I won't need the extra amp since that one is 11 amps already.
Plus I get a bit more power overall and some features I am curious about like imax enhanced or even auro3d.
Is Imax enhanced that big a deal in terms of sound?
I am looking at about $500 price difference to get the 6500h (minus the price of adding the amp for the 2 extra channels I will need for the 4300).