I have all the stuff listed in my signature (T2i, 18-55, 55-250, 50 1.8) and I've been thinking hard about possibly upgrading to a 5D. I never use the movie mode on my T2i, or any of the preset settings. I just shoot in manual and with the noise of the T2i at high ISO, I never really go above 600. I like shooting more landscapes/wide angle stuff so I think the Full Frame adjustment might help me out with that as far as losing the crop factor goes. Whenever I'm out with my camera, I find myself using the kit lens because with what I have, it allows me to go wide.
Has anybody made the jump? Any likes/dislikes about it?
Honestly,
you are way over thinking. keep it simple. keep it simple.
keep it simple.
5D of some sort, and a 50mm lens, and you'll soon learn that you can produce art(not photos, art). You do NOT need those other lenses.
For what its worth, I shoot with a very old full frame camera and a 50mm lens. You'll end up pushing your creativity more with one lens.

