Dylan777, it's on my shortlist, however I'm having to juggle some gear to get into the fullframe world. Fiscal responsibility and all that heartbreaking stuff. I was also let down to have to get a 5D2 instead of a 3, but it's a large price jump there too for an enthusiast-level guy.
I've done some preliminary testing, and so far neuroanatomist (love that name/avatar!) is 100% dead on.
Overall it's kind of a wash, which means I'd elect to keep the 24-105 for its' range and better EF compatibility (and red ring woooo haha).
Here's what I found:
1) The 24-105 is indeed wider and longer by a smidge
2) The 24-105 has just slightly better OOF/DOF for portraits wide-open, both quality and quantity.
3) Sharpness is a wash.
4) Camera-wise, the 5D2 has to jump one stop (or maybe a smidge more actually) to match a 7D.
5) Camera-wise, the noise levels at the comparable highish ISOs (7D-1600, 5D2, 3200) produce a comparable IQ/noise level.
6) The 5D2 can exhibit a pretty bad vertical banding if you have to push the levels, but the 7D isn't much good at 1600 (generally messy) in the same vein.
7) The metering is different for each of the cameras, and the color balance (when all set the same in ACR) is visually different... hard to say exactly, but looks like the 17-55 produces a slightly more saturated image with more yellow/green, however I liked the RAW image from the 5D2 better for moving forward with an edit.
The only thing I haven't tested are the center AF points on each in low light... waiting until post-sunset so that I can control the light in my living room. "On paper" they have the same EV working range and sensitivity/type, so you would think the f/2.8 lens would win out, but I'm not sure that I care about focusing in almost full dark with this type lens anyway.