The question you should ask yourself is, “Will this client notice/care if the Web site is occasionally unavailable for 10 minutes? An hour? Half a day?” Every client has their own threshold; you have to make sure that the client threshold is longer than the routine downtimes you’ll see at Dreamhost.
At Dreamhost you get what you pay for in terms of availability. They don’t accept phone calls, and it can take hours, often days, for them to resolve support tickets. I’m not even complaining – you get what you pay for. But this means I have spent many hours just sitting around with my fingers crossed hoping DH will eventually get around to putting a client’s site back up.
To recap: If the client is really important, it’s probably worth the extra money to use a host with better support and less downtime (you don’t have any “special needs” as far as I can tell). If, on the other hand, the client is not sensitive to downtime, then maybe DH is fine.