I must say that experience differ a lot. From my 140 D40+ balls zero cracks in 3 months. Yes, I do play in small club (2 sessions per week when out of season) and it's mostly minor league players so we don't care so much about the roundness. But ABS seamed balls are at least on par with Xushaofa seamless in shape and with half the price (through TTnPP or similar seller) and basically no loss it seems to be winner for us. If it has quality issues when you have high ball rotation (when running the gym whole afternoon and evening every day on 4+ tables with several hundreds of balls per month) that's a pity but I can confirm neither from my experience nor from other players I talk to here.
I
Well, previously I have discussed it here that may be there is some difference in the quality of different balls and brands here and in other regions, as well as different price policy, but thats another story.
What I say is my personal long term experience, same as the experience of many players around me too, and its mainly based on playing with personal balls, and playing with one ball, not multiballing.
Multiball is very different. With multiballing every single ball will have 5-10, or even 20 times more useble life, counting its active play only, as every ball accumulates much less heat and material fatigue. In my club we use different cheap seamed balls for multiball sessions and 1* seamless balls for the robots. We have 2 robots and they are a very good testing device for the ball shape and consistency. Seamed balls go out of the robot with unconsistent speed, trajectory, placement and temp, or just don't pass. About breakability - the usual case to brake a multiball is to step on it, rather than to break it in play, thats true, but we can't start with 140 balls and end with 140 after a month, what to say about 3 months. With 11 tables, 30 children and about 100 players at least 20 of the cub's balls go to the garbage every week, maybe more.