Ryon,
....and don't get me wrong. I'm not trying to talk you out of or into buying selling or trading anything. Your statement about the 5D2 being so good in the studio.....that is certainly true, but, and this is a big "but"......virtually every portrait shot you see posted on this forum could be taken with any of the DSLR's in the Canon lineup, from the rebel on up thru the 1DS3. Virtually every shot that you see that you think is good-to-outstanding has has some thought put into it from a shoot standpoint, and then has had some-to-a-lot of work put into it in post.
I'm not saying you would make the following mistake.....but I am just pointing out that some folks have bought better, more expensive gear, and then were disappointed that their photos looked essentially the same as what they had been getting with the previous gear.
Think before you spend. Nothing beats education and experience, and it's one of the strongest points of this particular forum: there are many folks here with a lot of talent that are willing to share their knowledge. Ask questions, post photos up and ask for honest critique. Sometimes the responses can be brutal, but you will learn if you take it with an open mind.