I have a factory RRA 9mm carbine, and I built a 9mm upper for my SBR. With the RRA block, I had to tweak the block position just a bit to get it to run 100% with:
OLD CProducts magazines
Metalform magazines
RRA converted Uzi magazines
...all three types of mags run fine with the block in the appropriate position. I'm not going to say I'm lucky, but I haven't seen a lot of positive comments about the old CPro mags - they were inconsistent in assembly and had poor QC, particularly at the end. The only one that gave me trouble was one I dropped, full, onto the feed lips.
My advice is to buy two of every kind you can find (except ProMag's plastic ones - they have always been too soft to handle full loads) and try them out. You can find Metalform 9mm Colt-style AR magazines at CDNN for a pretty good price when they're in stock.
The NEW CProducts Defense is a completely different company that owns the intellectual property from the old company; they use a lot of robotics in manufacturing their mags, which makes them much more consistent the old company's products, and they're still reasonably priced. ASC is a firm made up of former (old) CProducts employees who bought some of the intellectual property and most of the tooling of the old company. I don't know if they use robots or not, but they seem to make reliable magazines.