my nift fifty wouldnt focus whilst being used with the 5d when i had a play with it recently after a long while!
You will find little love for the Nifty 50 in this thread - http://photography-on-the.net/forum/showthread.php?t=563606. My comments are at the bottom of page 1 of the thead. See posts 21, 28 and 30 on page 2. I am sure many feel the same way. Add post 37, 46, 64 (me again), 77 (maybe), 85, 92.
Another thread, again with input from me - http://photography-on-the.net/forum/showthread.php?t=473649.
I haven't used the 85/1.8 or the 50/1.4 but both have had my finger hovering over the buy button. However, I'm still not 100% convinced that I wouldn't want the 50/1.2 and 85/1.2 instead. I know there is a massive price difference between the L lenses and the non-Ls but lenses last a very long time (hopefully) and if I can afford the best, which I can, then why not buy the best?
From what I've read and seen, if you're really never going to cough up £1,000+ then the 85/1.8 is an absolute steal. It will make a superb portrait lens, but is pretty long, at least on a cropper, for general wedding photography. When the B&G are signing the register you'll likely want something a good deal wider than 85mm. If you're the pro then you'll need something wide so you can get in close and fight your way past the elbows of Uncle Bob and the other pap wannabees. Then again, for the signing, once the service is over, you'll probably be OK to use flash, so you won't really need f/1.8 anyway, but 85mm will be no use.
I'm getting confused now as to whether your research is regarding a Nikon Nifty or a Canon Nifty. All my remarks (about performance/quality) relate to the Canon Nifty. For all I know the Nikon version is a different beast. Ditto the 85/1.8 - are you talking Nikon or Canon? I know you said elswhere you were planning on a D700 but I don't know which body you are talking about for this discussion.
If you want to see some wonderful work with the Nikon 85/1.4 then you should check out this guy (he posts here, I think, and certainly on POTN)....
http://meninenuotrauka.lt/