May I add my bit. If you were to pilot a tornado fighter and perform a sudden dive or climb, say - something crazy such as 18000ft/min the pilot who has had the gromets may be in trouble. Naturally having the gromets removed will cause scaring to occur on the ear drum, this is most likely to cause the eardrum to weaken slightly (in most cases). This weakening effect may cause the ear drums to suddenly perforate with the pressure differential. However, this is an extreme case and of course depends on the individual- everybody is different!
Maybe another far reaching question on health would be to ask what long term effect G-forces have on the body and hearing??