Motorola Droid :: Ok To Delete MotoNav Data?

I'm running out of memory on my Moto Milestone/Droid. From what I can tell, the app that is taking up the most internal space is MotoNav at 17.73 MB (= 17.49 MB of data and 248 KB of app). My trial period has already expired though it appears I can still use it now (I'm assuming with its existing maps).I've read it's hard to remove MotoNav from the phone because it's a system app. That's fine but what happens if I just want to delete all the data from this app? Is that ok? Are there any long term ramifications to do that? What happens if say, I chose to buy an activation key for it at a later date? Will I be able to redownload all that data (the maps, etc) again?