Thanks for this update. To tell you the truth, it's been so long since I used Zotero that I didn't know anything about ZotFile or ZotPad.

Thanks for the post. I pretty much settled on Sente a year or two ago and have surprised myself by sticking with it and not being too tempted by any of the other applications for which I also have licences. My feelings on Sente's strengths and weakness are a little different from yours:

1. As Christian mentioned above, it's actually one of the stronger applications for sharing (though having to buy multiple licences could be a problem): you can give a copy of any database to as many people as you like, and once they've installed it it will update itself indefinitely without further intervention. The syncing feature also has an impressive range of options: you can allow people to just read your database, to read and edit existing entries, or to do the above and also add new entries. And where digital rights don't allow you to share attachments, you can exclude those from sharing/syncing.
2. Related to the above, it's the only offering that, in my opinion, offers a good integrated system involving seamless syncing between Mac(s) and iPad(s). (I don't think much of the Mendeley iPad app in comparison.) I have well over 3000 PDFs in my library and the iPad app has recently started to slow down a bit, but until recently I didn't really have any problems.
3. The annotation system is in my opinion excellent. You can quote text by simply selecting it, and it gives you title and comment fields for each quote. Each note can be embedded in the PDF and in addition saved as text. If you take extensive notes on a PDF on first reading, on subsequent readings you can just refer to your notes and never look at the PDF again.
4. Unlike you, I find support on the forums poor. However, in the past when I had a major problem and contacted the developers by email, the response was rapid.
5. There are some weird gaps in basic functionality. For example, they still don't seem to have realised that an edited volume and a simple chapter in an edited volume should not be treated in the same way in APA 6 format.
Those first 3 points are the killers for me so I'm happy to put up with other problems. It should also be noted that the coming Sync2 is set to make the syncing features even easier to use: http://www.thirdstreetsoftware.com/blog/2012/12/s...