Ok, back to the topic at hand... and thanks btw for the PSA's, some bad coaches really do need to be outed.
Agree on the whole reaching out to the coach and joining one of their practices. That is certainly a good option and you're more likely to standout vs a normal tryout anyway (just my limited experience) and this is what I recommend if you're looking at two new clubs. But - if it is conflicting with your current club tryouts, I think it does say something about your satisfaction with how things are going and your gut is telling you it's time to move on to a different club, coach, or team... so given the choice, go to the new club/team tryouts. Your current coach already knows what your kid is capable of and has probably already made an assessment, if you're getting a new coach, most likely they've already assessed your kid as well or gotten the lowdown so if you really want to go back, then they'll either want you or won't.
The flip side to this is also realize that every team has its issues. It's easy to get into the whole grass is greener mentality and at the end of the day, unless you really think through your priorities (or your kids) and are aware of the trade offs, you're likely to wind up just as frustrated as you began. No club is perfect, no coach is perfect, and no team nor player is perfect. If you can surround yourself with good people, good kids who share the same goals as yours (and you really need to think through what your ultimate goals are), and good coaches, you've done pretty damn well - likely better than most.