I've had problems with shared hosting in the past and when I contacted Invision about one of their shared hosting packages they said I'd need to look into a dedicated server as the shared hosting wasn't suitable. My site runs on joomla and Invision for the forum, it averages 2000 visitors a day and last month used just under 40gb bandwidth. The forum itself isn't that busy it averages 300-500 posts per day, but the issue with it seems to be the resources it uses when it's busy. It can range from 50 to just over 200 users online at any one time (most ever was 270). It's by no means big numbers, and I reckon a dedicated server is way overkill. Can any of you guys advise?
Forumhosters could host it for you on a shared account. Invision are probably mainly interested in selling you an expensive dedicated plan.
Clustered/Application hosting. Or even a VPS should do the trick. All are much cheaper than a dedicated server.
you can try dreamhost. my forum (500+ members + guests always online) is not that busy, but they handle it well.