Well, I took a chance and signed up for two years... Hopefully I won't regret it.
It says in my control panel that before transferring my domains to DH, I need to set their nameservers to point at DH. That may be a problem, as my old host has all my domains locked and aren't being very co-operative about either changing the dns information or allowing me to do it myself.
Switching hosts is such a hassle, I really hate it because it seems that every time I want to change webhosts, as soon as the old host gets a whiff of my intentions, they stop communicating.
The way I feel is that the way you treat a customer who is leaving your services says a lot about your company, at least as much as how you treat a customer who's staying...