well, yes and no. It's kinda safe to use the IP address. There's a good chance it will stay the same for a while, years even. But dremahost makes no promises - if they decided to re-arrange IPs for whatever reason, they can and will - and then your scripts will break.
I'd reccomend you use the name servers if at all possible. The current issues with the DNS are on the way out the door, so I think that you won't have any issues there.