Cannot stress enough how much stuff he already implemented.
Testing works out fine so far, he can apply fixes in a matter of minutes or hours and he is an all around very helpful person.
The Discord is frequently used and testing could always use a little bit more help, to test different machines and such!
So far this is looking to be a very performant backend solution for most of your MMO needs and you can just settle your game project on top of it without having to care too much about the server solution!
Also: Bump.