I will have both. I didn't go 2ZZ with my MR-S. I went Turbo and Meth injection. The FR-S will be a definite downgrade on all levels of performance for me due to my mods on the MR-S. But it will be my daily driver and will be slightly more practical while still being fun.
My MR-S will become a more dedicated project car now that I can leave it taken apart for lengthy periods of time. To compare the 2 is a little silly. Stock vs. Stock, the MR-S is lighter and better fuel economy. They are probably pretty evenly matched for performance. The FR-S is new though and has some nice new amenities in it that are missing from the MR-S.
Bottom line is (like was said previously by Genomaxter) just have both.
Also, I remember that video. Well done. The guy modeled the MR-S by hand in 3D. great job on it.