Not sure what you guys do for break in but I can't keep the gates belts together for ****. Both of my sleds ate them. 2-300 miles and they explode into 1000 pieces. Stock axys belts never blow on me, but by 300+ miles they are just worn out as can be and make the sled feel like a turd. I clean sheaves every other ride and just cannot seem to keep a belt in a sled especially the gates ones.
I'm pretty much in the same boat as you, stock belt is good for about 6-8 rides, then perf goes to crap and you cant get it back.
Gates belt works awesome until it blows apart. It did help doing the break-in. I try to get 3 heat cycles into the belt with out being hard on it. Install new belt, ride 5-10 minutes to get it fully warmed up, then stop and cool it down. Do that 3 times.
Works great if you do 2 new ones at a time, ride 5-10 min, stop and swap belts, then repeat. I would just strap the warm one to my tunnel bag to cool off.
At least they will give you a new belt when you blow it apart.
Edit.... Forgot to mention I also installed the MTNTK Blow Hole on both my 16 and 17 axys. Not only doesnt it kick out a bunch of heat, it also keeps the clutches cleaner by getting the belt dust out.