I've been in and out of various Gay-Straight-Alliances, groups at The Center and smaller groups by the local City Hall. I've also been in and out of a few online LGBTQ-friendly forums, and one all about LGBTQ topics.
Pretty much, they're fun to be in for a while--but they can get old fast. IRL groups are like any other club with a common interest--except, most of the time you share less interests with them than others you join a group or club with. Talking about your gender expression, gender identity, sexuality and such is exciting for the first few weeks. Or days. Or hours. After that? I just tend to leave 'em.
So, you know. Join 'em when you want to, enjoy them while they're there, and leave them when you get tired of it. xD