I've seen extractors setup many ways. I've seen them with the o-ring and w/o, and w/o the inner rubber spring. Some times another spring is used instead of the rubber inner. If your system is over gassed or running a SBR I would use it. If you drop the BCG on a round all ready in the chamber, the higher load may damage the rim. In any case it will probably not make any difference.
I normally cut 1 coil off of the Ejector spring, to keep it from denting the brass on ejection. Part of my tuning process when I build a gun.