Depends on the players
It really depends on the players, we have an outdoor field with multiple buildings so kind of a mix of CQB and regular play. Our limit is 400 FPS with .20 and no minimum engagement range.
We require full masks for under 19, adults can make their own decision.
Beyond that we stress centre of mass shots, in 6 years we have had a few bleeders but no serious injury.
You need to look at your environment and see what the potential for someone getting hit in the face at close range is. If there is a good chance, require proper googles and some form of mouth guard. Rent full masks at worst.
But ultimately you have have to decide not the players, after all they all think it is cool to be at 400 FPS until they get hurt.
If I was running a pure CQB location, with little or no vegetation I would go around 350 to 370, that covers most reasonably upgraded guns. Those who went to 400 will be left out, but they can always rent.