I'm using the original version, with Mk8 belts claiming 6000 items/min. I'm aware that the game currently doesn't really allow speeds above 2000, but that's not the issue I'm having.
Ultimately, I'm having issues with the Mk8 machines outputting items. Sometimes my machines seem to "forget" that they have an output belt attached and just don't send anything at all. Other times, they take far too long to start sending their output items on the belt (but do send eventually).
The first of those seems to get somewhat resolved if I take down and re-build the belt enough times, but even then, that solution is inconsistent. The second one I suspect is just because of the belt speed limitations (and thus, the belt is "considered full" even when it's not). I would like some clarification if this is actually a bug, or if this is, at this point, expected behaviour for this mod at this point.