"irrelevant" is badly chosen. I mean it is unavoidable to always have to send work updates, whereas tickets posted by the miner can be avoided by choosing a high difficulty.
I'm no pool operator (obviously), but keeping connections up will use up some memory and every client connected increases the latency. As I don't know the specifics I won't go into that, like I said, maybe CK can answer that.
I'll practice with the 'quote' button more so I'll only post a single reply to a topic instead of a reply to every post I quoted.
Yes indeed the 'ticket mask' decides on nonces returned, and yes you still have to send work every few ms for a number of BM1397.
Alas I'm not sure what this overpowered computer is that you seem to think you need.
For a single BM1397 you can run about a dozen on tiny RPi power
Anyway, that's not the case with an S19 chip - it does work generation in the chip - so you don't have to send work very often at all.