most people that use them don't report the same issues, but then maybe these guys are using full auto or something that civilians don't encounter. all i can say is the overwhelming feedback is thousands of rounds and no issues.
the scar platform in general has a reputation for outstanding reliability and this is also backed up by the armorers at Battlefield Vegas, where 100,000s of rounds are fired through their guns.
for me, not expecting to use this in combat unless there is a zombie invasion, i prefer the cleaner short piston system and being able to send more than a couple hundred rounds downrange before having to clean the weapon. the zombies won't understand the time out rules for cleaning my gun.