Here's a relevant help document from dropbox about syncing changes only: https://www.dropbox.com/help/8 I am not sure if this is available in the api you are using, but it definitely exists in the desktop client. Thanks for writing this app by the way. This was one of the things that android had that I wish maemo also had, and you made it!
Not sure if this is a bug or expected behavior but here is something weird I notice everytime I sync my Dropbox folders. Say, I have a folder called folder2 in my DropBox which is located inside another folder called folder1. So the path from my home in DropBox account is "/folder1/folder2" In the DropBox client on my N900, I have my default download folder set to "MyDocs/DropN900" and my sync path is set to "/folder1/folder2" Now whenever I try to sync my files, it Downloads folder2 and it directly under the default directly instead of first creating a sub-folder called folder1 and then put folder2 inside folder1. All files goto "MyDocs/DropN900/folder2" instead of "MyDocs/DropN900/folder1/folder2" as expected.