Here's how I think of things:
Non-member: Can be in the lab as a guest of a member, and use the equipment that way. Can be asked to leave at any time.
Associate member
-Can be in the lab and use the equipment,
-Gets member discounts on classes
-Can not have 24hr access or vote (although now they can vote in HYH).
Full Member: Everything an associate member gets plus the opportunity for 24hr access and the right to vote.
As someone who only makes it up to the lab every few weeks/months, this suits my needs fine. I don't care for the politics (although if there's a problem I'll try to do something about it), so I don't get excited about voting. If I decide I want to vote, I'll change from the $25 to the $50 membership.