If you're happy where you are I wouldn't change a thing. That being said, I very much prefer fixed clamps and a 6 point mounting system is good for me. Whether or not you would like the 6 point mount or not I don't know. Sure would be nice if you could demo a machine like you can a tennis racket.
It really depends on what you plan on doing with stringing. 6 point mounting is easier on the frame, but for how little you are stringing I wouldn't worry too much about it. Fixed clamps give better tension and you can string faster with them. However, since you string only a couple times a month I really wouldn't worry about it. I string about 6-7 frames a day, and I like having fixed clamps just for my own sanity, but it`s not the end of the world if you don`t. (I string on a Babolat sensor at work, and usually on a 5 star if Im stringing at tournaments.)
I break them both fast. PC lasts a bit longer. I usually break SB in around 6 hours and PC in around 10. At most, I'd leave SB in for around 10-12 hours as it does get quite harsh once it dies. PC is fine as long as it isn't notched and you should be able to get 12-20 hours out of it before it completely locks up and is useless depending on your bat speed.