Hi there,
I installed FC7T4 i86-64 on my AMD64 from the DVD.
Installation was mostly OK. I wrote down a few minor comments, but i don't have them here. I'll post them some time soon.
One major issue is that KDE doesn't work at all.
I installed both Gnome and KDE. The first time i logged in, it was Gnome and it worked mostly fine.
But when I tried to log in to a KDE session and received an error saying that the desktop closed after less than 10 seconds and showed the .xsession_errors file. I looked through it and saw that it failed to open a lot of libraries (sycoca, kdedm etc.), but the most alarming error was that it tried to look for an i386 version of some library but found that the architecture signature in the relevant file was i86_64.
I'd gladly send you the log, but i think that it was overwritten by later logins. (Is it possible to recover the older logged messages?..)
When i try to login to a KDE session now, i don't see that error about i386 vs. i86_64, but there are many other errors and the desktop doesn't start at all.