this is what I was wondering, although editing in fcp on a non retina screen may be a pain in the arse. Im used to a big imac screen but traveling a lot atm so i was thinking of investing in a macbook tbh I think I'll go with the lower 15' model. apple are using fcpx in all their promo for it so i doubt the performance can be thaaaat bad
Sorry, I assumed the specs were obvious, but yes working on a 2.6GHz 1GB 650M retina is faster than a 2.3GHz 512MB 650M classic MBP; I suspect that is much more because of the extra VRAM than the 0.3GHz CPU difference...
That was the best comparison I have from experience working with FCPX on the same 1080p project, I don't have access to two identically specced machines... Having to edit on the machine (our calibrated external was not available), the retina's IPS vs. the classic's twisted nematic display gave higher bit depth, wider viewing angles and less glare, and along with the brilliant resolution advantage makes the retina superior in the field, IMO.
As to which would be faster if the specs matched, well you are trading the fact the retina has an overclocked GPU against the higher resolution it has to handle; note this is not actually about "resolution" which the 650M can easily handle, but whether the need for different scaling/interpolation triggers slowdowns in Apple's crap graphics drivers!
In regards to externals, the Seagate goflex thunderbolt adapter works wonderfully with 3rd party SSDs, very fast throughput for HD editing.
if my laptop gets stolen, it's replaceable, my files aren't.