There exists bugs with mono-side which causes problems with x11 and etc.
First of all, x11 and similar require lots of sha3 protocols implemented and it's quite a time-consuming task. I've been able to pull the job with a library, but seems we are having problems with mono side.
And really maintaining both .net and mono parts are a bit hard which is the reason i decided to port it back to node.js.
Yet again, Microsoft has stupid decision in effect like not allowing more then 5 http connections to same server (ip) which prevents multi-threaded pools within CoiniumServ. So basically, these are all some-how fixable (given you accept the fact of huge effort needed), I decided to go the easier way to pick a language/environment that can play nicely with a server-software that can consume C++ crypto api's.
It's nice to see there's is more then enough interest on the project and I was just silently working on
hpool silently before announcing it. But given the interest, I think it's a good time to disclose it.