I personally love hooked tips in my brushes - but have never experienced them breaking...many pay money to have hooked tips...
The clumping is due to the hooked tips - just go over the knot with your hand a couple of times when it is dry and they unclump - one of my favourite past times
I know this sounds stupid, but do you take good care of your brushes? Warm (not hot) rinse, until no soap is in there, followed by cold rinses (for the hair follicles to close up again), towel drying and then letting the brush sit and dry? Decent wash with shampoo, vinegar, glycerine every 6-12 months?
I am just asking, because if there would be any issues with breaking hair, you would expect them to be in the dry climate here in Adelaide, and I certainly don't have those problems.