I have a 7D + 5D. I find the AF fine on static subjects and really enjoy using it, despite having a 7D as well. I rely on the 5D for wide use of my 28-75, and for the shallower DoF I get (using the 28-75 F/2.8, and 85 F/1.8).
Where the 7D still wins (for me):
- AF. Light years ahead of the 5D as soon as something moves. I was surprised by this a little as I have owned older DLSRs and I assumed the 5D would be much like the 20D, but I found it worse. In addition, the AF modes and customisation is significantly better on the 7D.
- Video, liveview, if you use those. I use liveview for astro shots but that's about it.
- The LCD, primarily for image preview. Checking an image for sharpness on the 7D is a beneficial process, doing so on the 5D is somewhat indicative but you can't be 100% sure until you bring it onto the computer.
- For AF reasons I don't use the 5D for action shots anyway, but if I did I would miss the multiple custom models on the dial as I use them on the 7D (i.e. at a recent airshow I had one set up for prop aircraft and another for jets).
- Similar to the above, if I used for action then the speed of the 5D would bother me. FPS, buffer size, etc.
- Pixels on the subject, if reach is a concern.
You have a nice set of lenses, and a 7D + 5D combo would probably work well. I'm unsure why you have a 55-250 still but offloading that might help fund a 5D. Some other thoughts on your lenses:
- The Tamron 28-75 @ 75mm F/2.8 on the 5D will deliver pretty much what you'd get from the 50mm F/1.8 on the 7D (i.e. similar field of view and DoF). You might decide you can get rid of the 50mm, or you might then like the 50mm on the 5D 
- If you don't shoot with the UWA much you may decide that 24mm on 5D is wide enough, and offload the 10-22.
- The 100mm will cover a wider field of view on the 5D than 7D. You'll either need to crop more or get closer to your subjects when doing macro (and if already shooting at 1:1 then getting closer is not an option without using your tubes).
I hope I haven't confused matters!