Ive been riding 3x since forever/never tried 2x. W/3x, I spend 80% of my time in the middle ring- small ring on big up hills, big ring on big down hills. Stated another way, when riding the flats, all my shifting is in the RD. But w/2x, I would think youre constantly going back/forth between the 2 rings. Also, when you shift the FD on a 3x, its = to two shifts on the RD. I would think on a 2x, a shift on the front would be = to three shifts on the RD.
Just curious!
YMMV