1. Kyser capos are no good (and that's being kind). Yes, IMHO, but I'm offering it. Too much spring pressure. They are cheap and fast to use ...but they often will pull sharp. Toss it.
2. Planet waves Dual Action offers one-handed trigger use so it's just as fast as the Kyser, but you can adjust the tension. Tada!!!
3. G7ths are great, love mine, but one-handed use is tough, if not impractical.
4. Make sure you are using the capo just barely behind the fret. If not, any capo will have the potential of pulling strings sharp.
5. And yes, if action is on the high (or higher) side, this will most certainly affect tuning when you capo, even if capo'd properly.
6. Also, each capo will have a slightly different radius which will, or will not, match the radius of your fretboard. A gross mis-match of these radii will require that you crank up the tension to get some strings to ring true, which will then pull the other strings sharp. Proper radius match is important. FWIW, I've found the Planet Waves match my Taylors fine!
Edward