On my Nereus, i usually go around 60-70ish .28 for prototyping and around 50-60 on .28 or .2 depending if i need finer details or just a functional print.

Right not i'm still dialing in my qq-s, but it handles 70 without breaking a sweat. I have set acc and jerk way down tho. Helped alot with ringing. Got a slight 1 tone ghost in certain directionchanges now.
Benchy, printed in 70mm/s .2mm https://i.imgur.com/X249Rfh.jpg

Next up is dialing in the circular prints. I have a slight oval atm.