I had a set of CAP's lower control arms on my Challenger. HAD being the key word. They cracked at one of the welds, allowing the LCA to bend slightly. I noticed the car sitting lower on that side and found the damage. This was with nothing other than street driving, although with 1.12" FFI torsion bars and 275/40/17 tires...
QA1 has done a lot to redesign all of the CAP parts, and the new versions look a lot more substantial than the CAP stuff. I actually don't think the CAP design was bad to begin with, but the welding they sent out the door was AWFUL. Cold MIG welds, little penetration, and they sent it all out the door. Had the welding been good, I don't think there would have been any problems with their parts.
I wouldn't have any problems at all running the new QA1 parts, but I would suggest pulling anything made by CAP. At the very least, I would pull anything CAP made, have the powdercoating bead blasted off of it, inspect the welds, and reinforce and re-weld anything that even looked a little suspicious. Just my .02. Had I done that with my CAP LCA's I could have saved them, but they're pretty much junk at this point.