It seems to me like there's a good chance that things would wokr out for you. Serving files isn't a big CPU usage thing at all, so if that's all you doing I'm betting you could make pretty good use of the bandwidth.
There's the 97 day money back promise, so you could always try it out. Make sure and turn on resource reporting and keep track of how many downloads you get and how much cpu time that takes. Then you should be able to make a fairly educated guess about the usability of dremhost for your situation. If it's good, stick around - if it's not going to work out get your money back.