Someone much smarter than me told me something interesting at last year's SharePoint Conference...it was his opinion that the AvePoint tool interacts w/ SharePoint's databases in a completely unsupported manner. I haven't had a chance to verify this myself, but I would recommend talking to AvePoint and getting an idea of exactly how it functions.
I'm not trying to rumor-monger here or anything, just saying that you may want to do some due-diligence and check it out (something you should do w/ whatever platform you chose). I haven't talked to anyone who was unhappy with the AvePoint product, and if it had major problems they wouldn't have been selling it so well in the market for as long as they have.
The big thing is to take Mike's advice to heart and take a close look at the various feature sets of each product. Most of them offer free trial versions of them, the best thing you can do is test them each out and find the best fit for your environment, requirements, and administrators. Take a look at how effective they are, how well they manage your storage, what kind of resources they require (DPM requires a recovery farm, which is more overhead), how usable they are, and make sure they function well enough to meet your recovery time objectives (RTOs) and recovery point objectives (RPO).