Newly installed, possible future problems ? Note they are installed in a YMCA with a huge shower load

What is the question or concern? Every shower/ diverter valve needs repair at some time.

As ma0641 stated, any shower valve will need repair eventually. However, you can sleep well at night knowing you made a great purchase, as (in my opinion) Moen is the best out there, and the easiest to repair if problems ever do arise. Just clean or swap out the single cartridge and its just like new again. Also, Moen has a life time warrany (for parts if you get them directly from the manufacturer) and great tech support.

As far as future concerns, and this is for any single handle faucet. The faucet cartridge, or cartridge assembly may need to be cleaned or replaced (only if problems arise) due to blockage from sediments or wear on the cartridge parts.

Once again, you should be more than happy with your shower faucets. Take care.