As for the first one. It seems it would be more inconsistent to push and relase a button the 2nd time as opposed to just releasing. You would have to hold your thumb at the same exact distance each time. Even if you are just touching the button waiting to press and release, You might be off of it a little or have it partially depressed without knowing.
Here's a thread on the trans trigger, I don't have an opinion on it.
http://drr.infopop.cc/eve/forums/a/t.../309102431/p/2