Actually, I upgraded to Studio 11 when it was first offered. I had an AMD Athlon 64x 2 Dual Core +4200 and was editing HDV. When I ordered the first HF100 I ordered a Dell with Q6600 quad core 2.4Ghz without paying attention to what Pinnacle advised.
The Core i7 is a bit faster in some ways but Pinnacle Studio is such a "hungry beast" that even with 8 virtual cores at work rendering still goes slow. Oh it's faster, all right, if I remember watching the Q6600 literally grind to a halt on some things. I learned to leave and go do something else for 15 minutes or so then come back.
What goes slow is background rendering effects, if you do color correction on a clip, then another processing effect, each one takes time. One short had several clips where I did 3 effects on them and I just had to walk away and watch TV for an hour or two, even on the Q6600. It does go a bit faster on the Core i7.
One thing I learned on the Q6600 machine is that the grapics card can make a BIG difference. It came with an ATI Radeon HD 2400 with 256MB on board. With that card it would barely handle the HF100 files if the cam was set at 1440x1080 12Mbps, one notch down from max. The other NLE I use would not even display video on the timeline in the edit window from 1920x1080.
When I replaced the ATI with an Nvidia 8800GT with 512MB things changed. Pinnacle Studio would now edit 1920x1080 17Mbps if I went at it very patiently and put up with an agonizingly slow pace. And the other NLE also worked.
The Core i7 machine is showing a few signs I may be real wise to upgrade it's video card down the road. It has an ATI with 512MB but I suspect we are really going to be better off with 1GB there.
The other NLE I try to use literally "flies" on this machine, but there are a few things I really can't live with that Studio does a lot better...
...So that's my story and I'm sticking to it.