Video FX work - any significant advantage to a Thunderbolt HDD?

I've just upgraded my editing laptop to the new Macbook 15" Retina with dual Thunderbolt.

I work in Final Cut, After Effects, Premiere, etc etc. I usually use FW800 external G-Drives as work drives, to pull footage from and render to. Some of my AE effects stuff can be reasonably processor-intensive - I mainly work with ProRes and AIC quicktime files.

Is it worth upgrading my 'work drives' to Thunderbolt models? The cost is high, but if it will improve my render speeds, then I'm all for it. However, if the bottleneck is more in processor/render speeds rather than transfer rates, then I might as well stick with FW800 (and use the Thunderbolt > FW800 adaptor).

Thanks