The problem I have with this new division of age groups is that the 40+ guys have the option of playing both 18+ and 40+ and most of them do just that while the rest of us under 40 don't have anything to play in the winter months until the new year. It's bs if you ask me. I don't think you should be allowed to play 18+ if you're playing 40+. In other words, you shouldn't be allowed to play double leagues at the same time. Pick one flight and stick with it for that season. You can't double up.
A lot of my friends and I end up just playing our own ladder leagues which aren't USTA rated because we don't have anything else to play in the off-season, while the old farts take all our slots.