With Dropbox, there's no problem having panels, throttles, tables, even roster entries open at the same time on different machines. I'm often in that situation. You can't corrupt files because Dropbox is not real-time sharing, each machine is working on a local copy.

The worst-case situation is that you open, edit and save the same (panel or roster) file on two computers at the same time. In that case you may lose one set of edits, or you may end up with both sets separately saved, with one having a (Conflicted...) added to the filename. You can sort out which to keep.

The other situation is that if you add a new roster entry on one while both machines are running JMRI. In that case you may have to "Rebuild Roster" later (with only one machine running JMRI) to see the new entry.

But at no stage do you get file corruption and every change saved (or deletion) in the past 30 days is fully retrievable and recoverable.

Many times I've used that to recover from a whoopsie while testing new code!