This by the Asian Efficiency boys may be of interest,
Thanks, Andrew (especially since they incorrectly were advocating putting their DEVONthink databases in a Dropbox folder).
Cheers!
Thanks for the link. It’s a good writeup on how he uses DEVONthink.
But I did post a cautionary note as a comment. He’s storing a database in Dropbox, which we do not recommend.
Yes, I should have picked that up. 
Is putting the database on Dropbox only dangerous when it’s being accessed by more than one user? In other words, if I’m the only one ever accessing that database and it’s only being accessed on my computer, is it still dangerous?
I do not know, others will be able to tell you more difinitively but in view of all the problems others have encountered I avoid Dropbox all together with regard to DEVONthink.
Thanks Allsop. Just to be clear, I don’t have my DT database on Dropbox nor do I sync with Dropbox. I just do a nightly incremental backup to the ‘Copy’ cloud service. However, if it’s safe for a single user to store the database on Dropbox, then I wouldn’t have to do the backup every night.
Personally as a matter of good practice I will still avoid dropbox!
I’m with Allsop.
I can attest from personal experience. Dropbox can destroy databases - and the longer you store it there the greater the likelihood you’ll lose some or all of your data permanently. The reasons are varied and technical, but have nothing to do with the number of users.
There are other readers of the forum who attest to exactly the opposite experience as I’ve had and say they have had no problems with storing databases in Dropbox. Unfortunately, that opinion doesn’t restore the data I and others have lost by going this route. 
OK, that’s good enough for me! I’ll leave my database alone and just continue the hourly Time Machine and nightly cloud backups.
However, I’m waiting and hoping for someone, Copy or Skydrive or Dropbox or something similar, to be able to do incremental saves to the cloud. It would make life simpler!
korm is correct that it has nothing to do with the number of Users, etc. Dropbox is not made to backup a live database like ours. Dropbox syncs files. A DEVONthink database is not a file, it is an ecosystem of files in a special folder that looks like a single file. And like any ecosystem its parts must be maintained in order and balance for it to function properly.
This is true of any app that uses a similar mechanism - we are not alone. Dropbox doesn’t sync iPhoto yet. Why not? Because similar problems exist. “But Dropbox is adding support for this!”, you may say. But if it’s such a trivial fix then why isn’t it done yet? (Hint: Because it’s not a trivial fix - and no guarantee of how reliable or flexible it will be (probably not very).)
Do people store their DEVONthink databases in a Dropbox folder and appear to get away with it? Sure. But we’ve seen enough data loss / database damage tickets and posts to say, “You may get away with it for awhile but eventually you’ll get busted.”