As one of the few people who actually cared about Extension:Collection bugs in some recent past:
I've seen some people reporting bugs against their own mwlib installations as some organisations don't want the public PediaPress renderer.
I understand that there are some performance issues right now - it would be certainly beneficial to explain in the beginning of the document "why are we doing this" and "what options do we have".
I also don't think that making Wikipedia to use the cool nodejs/redis solution and leaving Jimmy the casual MediaWiki user with mwlib is viable - users will be frustrated they don't get the same output as Wikipedia's on their wikis and there will be lots of unnecessary troubleshooting work. Not sure how going through replication of WMF setup will be possible for moderately advanced user who is not living in a Puppet world.