Has anyone here used gun extensively? https://github.com/amark/gun it seems to position itself as a competitor to firebase, and wouldn't have many of the issues mentioned in the OP
https://github.com/sjones6/gun-mongo
https://github.com/sjones6/gun-mongo-key
Anything else?
e.g.: from chain.js:
// TODO: BUG! Handle plural chains by iterating over them.
(obj_has(next, 'put')){ // potentially incorrect?
if(u !== next.put){ // potentially incorrect? Maybe?
A lot of comments like: // ugly hack for now.
Source: https://github.com/amark/gun/blob/master/src/state.js