I'm emailing this to the support ninjas as well, but I wanted to make sure I voice my opinion here. Let me describe what would be ideal for me:
I'd really like to be able to have one instance of an OmniGraffle document saved to my Dropbox that I can open either on my Mac and iPad.
When I open it on my Mac, make changes, and save, it would work the normal way (Dropbox is already where I keep most of my OG documents).
On the iPad, I would be able to browse my Dropbox within the OmniGraffle app, open a file, and as I make changes to the file, they would be saved to that same instance on the Dropbox (kind of like how if i'm editing on the iPad and leave the app it's all saved... you never have to save changes, but all these changes would go to the Dropbox).
Also, it would be perfect if once a file were "opened" from Dropbox the entire file was cached so I could make changes without an internet connection that would be updated on Dropbox once a connection is available. Bonus UX points would be if any of these "live" Dropbox OG files would show up in the regular OG for iPad "Diagrams" file browser screen with a special blue border or something to indicate they are stored locally but updated on Dropbox as they are edited.
I've noticed you guys are kickass at maintaining data integrity when keeping multiple data sources in sync (I'm a hardcore OmniFocus user across 4 devices) so hopefully you can pull this off if there's enough demand!!
I hope this isn't too uncommon a use case to consider for development. With the current way the OG apps are designed, I generally have a copy of a file saved on the iPad, I make changes, then I export to iDisk. I have to rename the file and delete the old one usually because the files I work with are sometimes huge and the Replace feature doesn't work. This gets very tedious as sometimes I can't remember if I "exported" the document on an iPad when I want to open it on my Mac and make some quick changes.
BTW keep up the AMAZING work with all the Omni apps!!!!!!!