It is unlikely anyone at Omni will say "no, we aren't going to do that" but as a practical matter, they've already got a range of sync options, and a lot of other more pressing projects to get out the door, so you might have a long wait even if they want to add this! I suggest you go to
http://sync.omnigroup.com and sign up for the Omni sync service, which is currently free and works well.
If you do want Dropbox support added (or any other change made), the best approach is to request it with Help->Send Feedback. That gets the request into the development database, whereas forum posts usually won't.