I have been with dreamhost for two years. I currently have 2 strictly business, 5 code monster, and numerous other plans with dreamhost.
I haven't had too many problems. some minor email probs earlier this year. I would recommend dreamhost. I don't know how many servers they have, but I gather it's in the thousands...so yeah, periodically you would find a bad seed.
They have a 97 (something like that) day guarantee...so if you find probs, you can request to be put on another server, or move on.