Weight and bulk of my F5 seems relatively insignificant considering I typically use it with a 7lb lens. Reason for choosing it over a lighter F6 was that it actually balances much better when handholding this combination. The F5 is also useful as one of the few film cameras ever to achieve a frame rate of 8fps without locking the mirror.
(Though I do admit that the F5 looks ridiculous and seems like overkill with the 50mm f/1.8 mounted on it.)
I'm probably more mainstream in this than some of you--when just goofing around, I'm shooting digital, but for something serious out comes the film cameras. In my particular case, that's a decently spec'd (understatement) Olympus OM kit.