Very difficult to do. I think you really need to think about what your child needs/wants in this sport, and then meet with coaches and listen carefully. If you have friends or someone you know/trust with a child at the other gym, that helps.
Here is an example of why it is hard:
Gym A, if you don't make preteam when you are 5 or 6, door hard to pry open unless your kids appears to be a phenom and fits closely with said gym's "physical ideal" in terms of strength, body type, whatever you are looking for.
You are moving to town and considering Gym A, and want to ask if that gym is appropriate for your 6 year old:
Parent 1 has a Level 10 at Gym A, headed to NCAA in a few years. "This is a fantastics gym. The best one in town. When we switched here four years ago, coaches and kids were really welcoming. The team and girls are fantastic."
Parent 2 child is in Excel at Gym A. "We love this gym. They have the option of Excel with only 6 hours a week. This is perfect for our child who is excels in soccer. We think her gymnastics contributes to her confidence, flexibility, and strength which benefits all areas of her life."
Parent 3 child used to be at Gym A, is now a successful Level 10 somewhere else. Well, Gym A was not a good fit for us. My daughter was not allowed any privates and she went unnoticed there. She has blossomed under coach at Gym B. We are sooo glad we made the switch.
Parent 5 used to be in Excel at Gym A. Our daughter was consistently over looked at Gym A because she started at age 7 and wasn't the strongest or most flexible, though she seemed as good on those things as many of the other girls who were invited to preteam, if a year or two older. While all the coaches said the most important thing was that each gymnast progresses, she was never given the opportunity for more hours and the top coaches at Gym A. We are so happy we left, and our daughter is having fun scoring better than many of Team A girls who were picked over her a few years back. Next year is her first year of options, we are looking forward to that. Our only regret is that we didn't leave sooner.
Parent 6 "I've never been to gym A, but we would love to get in there. They send more kids to NCAA than any gym in this state, I think."
Parent 7 "You must be insane to encourage this sport. I'd rather watch my kid at the ice rink or out in the sunshine."
Depends who you ask. The trickiest part really is finding the right fit for your child, who want to see her do her best even if she may not be on the national team one day. Or maybe she will.....but she needs someone who believes in her..
Good luck! If you are a coach you probably have more of a leg up on all this than the rest of us did at the beginning.