Forgive me for a MBP vs iMac question

Please forgive my post as I'm sure people are tired of this question, but I'd like to ask with details about how I work.

My current MBP is an early 2010 with the following:

3.06 GHZ Core 2 Duo

8 GIG ram - 1067 MHZ DDR3

NVIDIA GoForce 9600M GT 512 MB

I bought this to edit video, and it has worked great. Just a side note, I bought this and 1 month later the new i7's came out!! Ugh.

Anyway, as I was saying, it's working fine, but now that I'm using FCPX and Motion, it's acting a bit tired, and I usually get a new computer every 2 years anyway.

My question is this, will the new TOP of the line MBP provide a noticable difference from my current MBP? Or should I be leaning towards a new iMac?

Second question is this, is the top end iMac faster than a top end MBP?

I'm interested in pure performance, so portability isn't an issue.

Thanks

Tony