Looking at a new system... which one?

Hello folks,
I am just starting out with FCPX. Currently I'm running an older MacBookPro with a dual core something... it's about 4 or 5 years old. I can't edit well b/c it's so slow. SO...

I'm looking at a new system that apple is offering now. Weighing budget, portability, and power is some what challenging. Here are some of my options (basically what Apple is offering now)

iMac 3.4GHz - Mini at 2.0GHz - MacBook Pro at 2.7GHz

Which would you choose and why? Portability is not super high on my list, but it is still there.

Rumors are saying that an iMac refresh is imminent. If you can I'd be hanging off for that.

If not, definitely go the iMac with as RAM as you can afford.

The iMac gives you the most bang for the buck.

What about the Mac Pro 6core 3.33 with this configuration i.e. see attached photo?

Maybe I should just go the Mac Pro route. Only it's not USB 3. Wonder if that matters much?

On those three options, I would go for the iMac with 1TB HDD and use the $500 you are saving from the SSD to buy an external RAID like this one from G-Drive (3TB RAID-0 for $ 450!)

www.g-technology.com/products/g-speed-q.cfm

If you find one RAID-0 system with FireWire 800 and USB3, I'll buy that one. I suppose the next iMac will have USB3, which is faster than FireWire 800.

I'm also looking to update my hardware. But I'm inclined to go the MBP way due to the ivy bridge and the portability and of course the fact that I already have a display. I am, however, a bit concerned about NVIDIA GeForce GT 650M 1024MB that Apple has put in their newest MacBook Pro line? Has anyone had any experience with it?