http://www.teamfortress.tv/2480/prem-invite-mouse-settings
This thread has the sens of a lot of old prem/invite players.
Posted in that thread is:n
Soldiers
Avg = 7.66025
Std = 3.5195940686
Min = 1.818
Max = 13.636
So I guess lower (higher number) than 10 is pretty low.