I'm using CBrandin's 66mbit GOP2 settings. I have two 16GB Sandisk extreme 30mbs cards, and at 66mbits those are chewed up in 30 minutes, so I imagine at 176mbits with i frame only the files would be absurdly large. I guess I will try it out though. Are you using driftwoods patch? How stable is it?
Honestly I was more concerned with the 60p mode anyway, since I was already happy with the quality out of the cinema mode. And other than just resolving more detail, it should help with grading and noise at high ISO. Hopefully I'll get a chance to test that out in the next week or so.