How to tell MCNs are wet?

I've just started using MCNs today, have mix of AIO & pockets. For the sake of sounding like a dumb bum - how do I tell if they're wet? The material that's against his skin seems dry so I've been taking the entire nappy off & pulling the insert out, which I then find is soaking wet. Is there an easier way?
DS usually needs changing every feed (3 hourly) in sposies. Should I be changing him more frequently in cloth?
Thanks in advance.

I'd say change 2 - 3 hourly. After every feed should be ok :)
I can usually feel the wet through the inside of the nappy, but DS rarely keeps them on long enough to get too wet, when he does they are usually leaking after hours coz he refuses to take them off!

Yeah I just change every 2 - 3 hours, depending on what nappy they are wearing.

DS has a habit of outwetting a nappy in an hour, so I do keep a close eye on it, otherwise I have to change his pants as well ;)