Well, yeah--the software installs can be a pain. I used to reinstall every six months just because I liked playing with new OSes. However, the rest of my life has become more demanding, so I am cutting back. I stayed with F12 until EOL, and did the preupgrade thing just to get to F14. Still not sure how I like the results--It still seems like F12, but with some newer packages.
I'll probably stay with F15 until EOL, then go to whatever version is newest at the time.
I think they currently plan to EOL every release 12 months after it first comes out - so FC14 has 6 months left to run and FC15 has 12 months to run. 1 year seems about right to me - after that might as well bite the bullet and get back on the leading, if not bleeding, edge!