I only have one pair of Komorners and an extra little roller cross. I have not lost a pigeon to hawks since last year. It all depends upon your location I suppose and how open your property is. I do not have to keep up with the losses because I haven't had any in quite some time.
We have a pair of Redtails and a lone coopers hawk that make rounds of the property from time to time, but once they show up the pigeons start to zigzag and spiral away from the hawk. My pigeons just out manuver the hawk somehow.
I do lock up my young birds while they learn to fly. It helps with the losses. Young birds are clumsy fliers until they learn the ropes.