My wife and I will be flying SAT-SFO in a a few months on an A319. A couple of questions. (FWIW, I'm tall and she's not.)

1. From a purely legroom point of view, how does exit row 21 compare with row 1, with and without cut-outs in row 1?
2. Any sense of how often the two versions of the A319 get swapped, such that we could reserve row 21 as the exit row but end up in another row if the swapped plane is one that has 20 as the exit row?

Thanks for any help!