Honestly, there probably isn't a really compelling reason to switch, if you've been able to survive through DNS caching. Dreamhost's customer service is good, and their problems mostly stem from the fact that they do the exact same thing every other budget shared hosting platform does: oversell like crazy, cross their fingers, and hope that their users don't actually use all the storage and bandwidth they've been promised. The only difference I can see is that Dreamhost is probably the most popular such service, so that strategy bites them in the ass more often than others.

For me, though, having relied on more than just registration and DNS through Dreamhost and gotten screwed too many times, moving to Webfaction made a world of difference. Their shared plan isn't as solid as dedicated hosting would be, but at least I can say I get what I pay for. With Dreamhost, that much wasn't true.