Looks good, from whatever I have seen and read. I am going to give this a try.
A question to those who have used Zotero:
Can I opt to store everything on the local device and have zero data transferred to the server? Is there any kind of control over what is stored locally and what is sent to the servers?
By default, you can use Zotero without logging in, which will cause it to keep everything locally. It's not obvious how you might go about partially syncing to the cloud, however.
In practice, though you shouldn't store the SQLite in a cloud sync service, setting up a symbolic link for the backing PDFs in e.g. Dropbox works quite well and gives you more control over your data syncing. Then, you only need to rely on their cloud for the paper titles and metadata.
My recollection is that it is all local by default. If you don't specifically connect to their web service for syncing data, none of the data is stored outside your local device.
A question to those who have used Zotero: Can I opt to store everything on the local device and have zero data transferred to the server? Is there any kind of control over what is stored locally and what is sent to the servers?