from my own experience the jap pillowball arms (cusco, tein etc) have lasted years. but i guess my use of the pillowball arms and most of my customers are casual and not top end race use so they been low maintenance.
we do slam our cars into ripple strips at high speed quite often so id think that would be a good test.
almost all aussie drifters use pillowball arms and even more jap drifters use em.
as SK says, they are best for track, and aussie drifters like to use whats best for what they use their cars for. they dont care if its not legal on the street, as most mods are not.
in the past 2 years have only seen some tie rod pillowballs wear out and require replacement (free with warranty)
all caster/camber arm replacements have been from incidents involving collisions with walls etc. just as someone pointed out before. they dont wear out that fast.
so id have to agree, bushes are best for street cars.. but i wouldn't bother with them for drift/track based cars.