Xprotector is quite unstable, really good for crackmes I think, but not for commercial appz.
It adds a heavy overload at your program (and make your program's size incredibly grow), and sometimes neven can be run well. Btw, if you don't add a heavy protection (I mean, not using 2000 de/crypting layers and the other things it can provide), sometimes could be useful.
For the discussion about ASprotect vs Armadillo, I can say only that I read some tutes about asprotect's manual unpacking and I found its methods very interesting.