Tapastic is actually the only online forum I've ever participated in. I think the community here is very friendly, and you can usually disagree with people without it getting nasty or disrespectful.
There are only a few instances where I've thought that some people have been unreasonable in the way they've addressed others (and the few times I've seen it, it's been on topics that aren't actually "loaded" or political or anything, it's usually on rather neutral topics, if that makes sense). But no one has ever been unreasonable or harsh with me here, I've only talked to nice people I guess 
And that's probably got to do with the fact that our usernames are tied to our work. You don't want to come off as an unpleasant person when you're here in professional business. And for me personally, this forum is a great way to connect with others like myself - I don't have much of a comic creator network around me, tapastic is pretty much the only place where I can talk to other comic creators and share ideas and hear what they have to say on things. Now I've been on summer vacation for a while, so I've had extra time to be active here, will probably be a lot less active once I start working again...
But yeah, I can get nervous about commenting sometimes too. I've always been self-conscious about how I express myself, and especially because English isn't my native language.