I also use Zotero, and use Box.Com for storage/syncing. Zotfile is a wonderful addon.
I use Zotero in conjunction with Papership (http://www.papershipapp.com) on an iPad. Papership syncs with WebDAV storage, which means that, after syncing, downloaded PDFs are available on your iPad for reading offline. Any annotations are pushed back and available in the Zotero client. It's a great client and really stable. In conjunction with the Apple Pencil, it's a really nice system.
I'd advise an iPad Pro 12.9" if you do a lot of reading. The extra size means that you spend less time zooming in and out, and an app like Liquid Text (http://liquidtext.net) comes into its own for bringing text and figures into the same region of the screen and reduce the amount of time you spend flipping between the two.
So if I understand you right, for syncing your bibliography you changed the "Data Directory Location" to a synced Box folder (a dropbox-like system)? I thought about doing so with owncloud, then I decided that paying when I reach the syncing limit would be a nice way to encourage the project.
Papership and LiquidText looks really nice, I would love to see such applications for Android. But I presume Apple is a more interesting platform as many researchers are on MacBooks. I suppose this is because researchers have really few spare free time and they don't want to use it fighting against the (linux) machines.
That might be part of it. Myself I value most the differences in hardware: I used a Samsung Galaxy Note at first for similar tasks and loved it, using Zotfile and Dropsync for keeping PDFs on the tablet. I travel a lot, and I couldn't count on it getting through a day of mixed use. In the end, the excellent power management of the iPad was a big advantage.
Similarly, I made the switch to a Macbook Pro after a bad day in 2011 in which I was first unable to connect my (Linux) laptop to a projector when visiting an institute to give a talk, and then unable to Skype in to a conference call. It was a bad morning, away from base, so I went to the Apple shop at lunchtime. I value the Linux box I use at work, and enjoy working with its tools, but easy collaboration is also important to me.
I use Zotero in conjunction with Papership (http://www.papershipapp.com) on an iPad. Papership syncs with WebDAV storage, which means that, after syncing, downloaded PDFs are available on your iPad for reading offline. Any annotations are pushed back and available in the Zotero client. It's a great client and really stable. In conjunction with the Apple Pencil, it's a really nice system.
I'd advise an iPad Pro 12.9" if you do a lot of reading. The extra size means that you spend less time zooming in and out, and an app like Liquid Text (http://liquidtext.net) comes into its own for bringing text and figures into the same region of the screen and reduce the amount of time you spend flipping between the two.