I would rather lose neither. I like Tsubame-gaeshi now that it has 2 charges (since that means I don't need to track the cooldown like a hawk anymore).

There are plenty of ways to reduce samurai's button count that would have virtually no effect on the gameplay. Most of them have already been noted all over the forum, but I'll bring up one that I haven't seen elsewhere: merging Kaiten with Iaijutsu.

"It's just a button you have to push every time before you use Iaijutsu." I mean, yeah, if you're doing your rotation correctly - so how about actually merge those two and make that statement literally true. Got your stickers? Use Kaiten, same button turns into Iaijutsu, use Iaijutsu, done. Got Ogi? Use Kaiten, same button turns into Iaijutsu, ignore it, use Ogi, which consumes Kaiten and turns Iaijutsu back into Kaiten. Ideally Kaiten is always paired with Iaijutsu/Ogi - it isn't used with other stuff nor are Iaijutsu/Ogi used without it, so no reason it couldn't "evolve" to Iaijutsu, just like Ogi could evolve from Ikishoten.

Also, another "I'd rather" that I haven't seen elsewhere: keep Kaiten and ditch Shinten. Spamming Shinten is horrible, but imo the idea of weaving Kaiten for Kasha or Gekko now and then actually sounds like an improvement compared to using Shinten as a dump.