What is 'low hashrate'? Is there a FAQ on your vardiff algorithm?

I run separate workers, each ~1MH/s, are they individually low hashrate?
Should they be on the low hashrate port or dogepolis?

What's optimum for the variable difficulty?
Should we try for just lower vardiff than the worker's average hashrate?

P.S. I'm also seeing almost 10% rejections right now.
Not complaining, just adding another data point.

Thanks for all your hard work,
and for any answers to my questions above.