I've got one and it definitely allows me to pull hoops longer before I get tired.
Mines set up overhead:
I like an overhead boom because you can pull the net completely out of the water with it, and I've lighted mine so I can see what's going on when I make my pull.
One thing that's important is that you do not want the pulley to be too far out off the side of the yak. The further it sticks out the more twisting leverage it has an if you mount it way out it will try and pull you over. Mines up high but it's actually pretty much even with the side of the yak as far as COG is concerned. It's not about getting the net off to the side, it's about getting a mechanical advantage that allows you to pull faster and more often before you wear yourself out.
Jim