I've flown lots of DMS motors, and the only one that I ever had an issue with was the L1000. The first one I flew blew out the front closure so violently that it sheared off the Aeropack retainer ring and spit unburned grains all over the playa. The second one (it was at ROCStock, so Aerotech was there to give me a warranty replacement) seemed to work fine, until I got it home and pulled it out; its forward closure had also failed, probably very late in the burn, but the rocket had a hard bulkhead in it so there was no damage to the rocket. That was 3 or 4 years ago... I flew one last year, and had no problems, so I'm assuming that they have solved their case/closure issues.