Joy, no, after a month at Aimoo you don't have to move to Diamond Class. What happens after you're at Aimoo for over a month is that you get these pig ads in with the messges, if you don't want to get the pig ads, you can pay for Diamond Class. But you aren't forced to pay for Diamond Class after the first month. A group I am with went over the one month date a few days ago, and is still there. Stupid pig ads are in with the messages, and I really hate them, but I'll hopefully be able to get used to them.
I haven't checked out Ning - but I will.