Speaking from my own experience, not from paranoid "I knew someone who knew someone...".

In 40+ years of shooting air guns (spring and pcp) I've never had a failure that I didn't cause myself. That one failure was taking a bite out of the o-rings when re-inserting the barrel on an S400 after I decided to do some preemptive maintenance - never again. And, as for them Daystates, my mk4is has never missed a beat or been serviced. Now where's a bloody great lump of wood for me to touch!