or have options to make some guns have tracers and some not. Make each gun/gun type have an option, rather than one blanket cover-all option - eg in a 109K4 make the 30mm can have no tracers, but be able to set the 13mms with tracers etc.
I prefer tracers off, but it would be nice having a bank of MGs with tracers on for scaring people etc, while the cannons are tracers off for the killing part.