Have members here had much experience with eXist as a native XML
database platform for TEI (P5) databases?

I have heard that eXist has had issues with performance with large
amounts of data and numbers of simultaneous users, but that recent
versions have addressed those concerns.  Is that true?  Have you hit
limits on what eXist can handle?  In particular, are there limits to
threading, the number/size of documents, engine performance?  Do you
think eXist is 'ready' for prime time use?

Can you recommend examples of eXist-based TEI databases that have a
large body of data and/or number of users?  (Even better, are there
usage statistics?)  I've seen the examples listed at - but
it's difficult to tell the volume of data and usage that they get.

Basically, I'd like to avoid getting too committed to eXist, just to
find out that I hit a performance wall and need to go with a
commercial implementation such as Mark Logic.  (My database will start
with about fifty 800+page digitized volumes and eventually hold up to
400+ volumes, and it should support 15-50 simultaneous users.)

Thanks for any guidance you might have!