My current camera is a 400D (Xti). This was my 1st DSLR although I've had Film SLR's in the past. I picked up the 400D refurbished by Canon (from Adorama) for $299 last January. It's been a great camera. I've learned quite a bit about DSLR's by using it this past year and I've decided to make an upgrade (ie an eventual upgrade was the plan going in).

I've narrowed the upgrade down to either the 7D or the 5D MK II. However, I'm leaning heavily towards the 5D. My current lenses are:

-EF-S 60MM Macro
-EF 85 1.8
-Tokina 12-24

If I go for the 5D MK II, I'm planning to get the kit which includes the 24-105 IS. Sadly, would have to sell the 60mm Macro (my favorite lens) if I go FF. However, I think the 85 1.8 would be a nice "prime" compliment to the 24-105.

My question is: Could I use the Tokina 12-24 with the 5D MK II? I know it's designed for crop bodies. However, I notice that it has both a Red and White dot on the mounting (ie it would mount on a FF body). Also, I recall reading posts about some using this lens on the original 5D and that it's usable from around 16-17 MM and up. Not sure if this is the same for the 5D MK II? If so, what kind of IQ could I expect from this lens on the 5D MK II? I'm just hoping to be able to leverage 2 of my existing lenses if I opt for the 5D MK II.

Thanks in Advance for the help.