If you're doing this at work, you've probably got fast, reliable connectivity for your iPad, right? In that case, you've got Dropbox access from the app, right now, using the DropDAV service. Just save the file back to Dropbox after you make a change, or at the end of the time you're using the iPad, and fetch it from Dropbox when you start working on the iPad. You've got a local backup copy stored on the iPad so you can access it when you don't have connectivity. Unless your files are very large, or you switch between them like a toddler on crack, the time spent shouldn't be an issue. It would be nice if the saving of files could continue in the background after switching to another app, but the Dropbox app doesn't seem to be able to do that, either!
Now, if you are frequently without internet connectivity on your iPad, this is more of a challenge, but sitting at your desk at work, bathed in speedy WiFi, this is more a case of convincing yourself there's a problem. Sure, life would seem easier if the app supported Dropbox syncing and did the dirty work for you, but if you give the matter a little careful thinking, you'd realize that you would still have some of the same issues if you can't make the assumption that the iPad (or any other device that changes files in your Dropbox) is always connected and able to sync immediately after making a change. Edit a file on your laptop on the plane and don't connect to the internet after landing? Oops, that change isn't in your Dropbox! Colleague puts a file in your Dropbox with details for the presentation you plan to work on during the flight, but you didn't remember to connect the laptop to the internet before heading out? Oops again. Yes, Dropbox makes things easier in an always-connected environment, but once you wander away from that simplifying assumption, there will likely come a day where you find yourself wishing you had handled a few more of the details personally :)