Roux alg halp D:
For the last step case, swapping 4 centers. The alg I've been using was E2 M' E2 M. The only other way I know to do this is U2 M2 U2 M' U2 M2 U2 M'. Neither of these options are fast, the length of the second takes away from the advantage of not regripping.
So I started doing (U2 D2) M' (U2 D2) M', which is just E2 M' E2 M. I do the U's with my left index finder and the D's with my right ring finger, flicking them simultaneously. While it's faster for me than the other 2 (and looks cooler), this is still my worst case for the last step. How do fast people perform this one?