30+, ΘΔ &, ABDL/hypno/other things account. Into many odd things. I hope you stay anyway~
Big agree on keeping diapers an RP thing and keeping them far away from mechanics.
I've tried to play a game that had, uh, continence checks basically and it was honestly a huge pain in the ass to try and track. Honestly, most mechanics I've seen people try to come up with make diapers a detriment and start stacking penalties! That's no fun for something the players should be enjoying!
I would still track their diaper status with a little white board card. To make it fun, I would have a little diaper stencil and color it in! It would get old after awhile though, so this would definitely just be a one shot kinda deal.
That's my observation as well. I want to encourage my players to wear and use diapers. I don't want to provide mechanical reasons for them to avoid wearing diapers.
Also, I'm a GM. I have a lot of stuff to keep track of. Checking on diaper stuff is fun the first couple of times you do it. But after a couple sessions it feels very samey and just takes up time.