I can't see any reason to NOT back up the community to Dreamwidth other than the time someone has to take to do it. But if there are people willing to do that, I can't see why we WOULDN'T-- more visibility, the chance to attract new people if people are boycotting LJ for various reasons, and a backup in case LJ decides to fuck everything up as they do on a regular basis.

As for actually moving, I'm not putting in a vote because I really don't care. I'm on LJ more often than Dreamwidth, but I have accounts with both and check both fairly regularly. In general, I support DW's underlying philosophy more than LJ and I'm always happy to see new content over there-- but I'm also pretty entrenched in LJ for a variety of reasons (not the least of which being that I've been here for something like eight years now).

I would like to point out, though, that it's important to remember if people have been turned away from the community by the LJ changes, they are unlikely to see and vote on the poll.