I have two RR that are Sendra Corp., love them both, before I purchased them I dug around on the internet and best I could tell they are built exactly to Colt specs. I've never heard a bad thing about them from the owners, heard a few Colt guys dump on them, but there probably a little bias. Purchased one about 4 or 5 years ago for 12K and the other 2 years ago for 14K, Colts were about 4-6K more then, one sold the other day (Sendra) for 16K, I'll let my kids worry about selling them, I'm just going to enjoy them.
I think the Shrike is one of those uppers you have to tinker with before it runs, I've heard horror stories about them beating up the RR, every time I check, so far, mines running without damage, but I need to get some belts out and try again. If you run across anything interesting about the Shrike, shoot me message. Also, I'll check over at ARForm and read up on it.