I picked up one of THESE for an SBR lower I have but was wondering if I'll need a different buffer.  The one I'm using in it already is just your standard carbine buffer.  I'll be using a YHM Phantom Ti QD 7.62 can on this rig.  Am I GTG?  

Also, I was regretting not going shorter (8.5-9") but plan to hunt with it and thought the extra FPS might be better with the 10.5.  Is this sound reasoning or am I trying to over think this?

You will probably need a heavier buffer.  AAC recommends an H2 with their 9" barrels, and many folks I know (myself included) run a Spikes T2.

i thought the consensus was that the standard car buffer was the way to go, that there often isn't enogu gas to cycle the heavier buffers.??