I used to be a monitor there last winter. in general the gym is more popular on weeknites than weekend nites. there could be between 2 and 15 there at any one time. usually it's 8-10. if I remember correctly the hours are 5-9. they don't have a rock gym membership per se. you have to buy the full gym membership which is $50/month.
as of last year the routes didn't get changed hardly at all. it was the same old same old all the time. pretty boring. the Cranmore company puts exactly zip into the facility. my friend Steve Angelini is working there this winter & from what I understand his job is to red all the routes & generally make it better. if so, I would say it might be worth checking out. if I were you I would just go by one evening & have a look for yourself.