I have had both Hamskea and QAD. I have personally liked the Hamskea better. I will say this, I was a QAD guy for years, until I watched one fail.
Long story short, friend of mine had a nice bull that he shot 4, yes 4, arrows at. Guy is a really good shooter and none of the shots were anywhere remotely close. I can't believe the bull stuck around as long as he did, but he did. We got back to base camp and found that the rest was not dropping all the way down. It was even peeling some of his fletching's off because it was still so vertical after the release.
It was a really dry year. Come to find out, some dust had gotten into the mechanism and was causing the launcher to not drop out of the way completely. Watched him shoot all week with no issue and then it fails with a bull in bow range. That was a tough one to be a part of...
I personally have never had any issues and every QAD I have used has been flawless. I have switched to the Hamskea solely for the fact that (in my mind) as long as the limb is moving, the rest is dropping.