how is FCP 7 on nMP 2013 6 core?

Anyone tried it? I'm thinking of buying the mac pro 2013 model...6 core...just curious how it runs...

FCP7? Cuz why? Why not FCPX?
7 should run fine on a nMP, but it is not optimized to take advantage of more ram, multi GPUs and lots of other things. If you have a fairly recent MP, then not much improvement in speed, especially true if you upgrade GPU.
FCPX however is built for new hardware and OS. IMHO the only reason to work in FCP7 is if re-editing an old project (use 7toX and edit in X) or you need to interface with an another/older program that cannot handle FCPX.
The other problem you will face is that legacy FCP(5.1.4-7.x.x) does not have the proper installer and Apple blocks installation, so if installing onto a new system, you have to use Migration Assistant (I do not recommend MA, do a clean install and manually copy documents you need) or you need to use Terminal or do some minor "hacking" to get it to install.
See this discussion thread…http://www.kenstone.net/discussions/read.php?3,44764,44764#msg-44764
Hope this helps, Greg

my current MP is 2009 quad....8gb ram...
well then...according to the link you provided...it appears that i have to use FCPx...which i haven't really tried it as much...i'll try that then.

Get some good training for FCPX and you'll be glad you made the change.
Rule 1 of FCPX training, forget everything you know about FCP7, NOTHING translates over, you're learning a new system from scratch. But X is way easier and faster to learn than 7.