cjs9870: I've been opening guard this way for over a year now and I find that when I use my arm to keep ahold of the bottom guy's wrist, it makes it very hard to stand up as erect as possible. If you aren't standing straight up and leaning back, then the guy will often climb his legs up for a higher guard and pull you back down.

Another problem is that if you leave one arm down there to control the wrist, the opponent will just use his free arm to grab your wrist. That puts you dangerously close to armbar territory.

When I was first starting this, my instructor pendulum/flower swept me almost every time if I left my arm in. I would say just play around with it in your gym and see if you have any success with holding onto his wrist.