The way I overcame the 'stammer' problem is hit the stomp button slightly before the first beat of what would be the next bar if the loop was continuing; pretty much like if I was playing a ghost note to slide into the intended note, if that makes sense.

I always found a noticeable, and extremely annoying, delay if I tried to end the loop exactly on the beat.

I've known a few guitarists who can't get on with looper pedals, but they have no problems playing in time with metronomes, click track, drummers, etc.