I am on my second coach now, not as a result of any issues, but purely because they rotate every few months for some reason.
My first coach was good, friendly, and I managed my first 4 levels with her, and was a little apprehensive about the new guy, as I had heard he wasn't particularly special.
However, the new guy (as he shall be known, though he is far from new), has turned out to be excellent. He breaks up our groups of exercises to prevent too much fatigue, and breaks things down in terms of the physics and body mechanics.
When I passed that 3-turn yesterday, I just found myself thinking 'I can get through this level, with this guy coaching me'. And that's about the highest praise I think a coach can get from layman like me.