I think this is enough responses for now. Here's the data:
Now it's time to draw some conclusions:
- I've decided that being as compatible with Zotero as possible is a top priority. This is due to the fact that most people have voted for Zotero as their primary Reference Management tool.
- It seems like there's a diversity in the size of BibTeX files used by the users, so I won't draw any decisive conclusions for the time being; let's leave that to a later time. The purpose behind this question was to decide if it's worth it to account for large BibTeX libraries (e.g more than 1 GB) since they will be difficult to handle without having a performance drop.