Just got a set of the X high rings to go on my AR. These are my first set of tactical rings so my experience is very limited. Pros: seem to be well made, light for their size, seem to hold scope well, price is reasonable.
Cons: Very large( I guess most tactical rings are), made of aluminum (can strip if torqued too much).
Like I said this is my first set of tactical rings, for what it's worth I would buy another set if needed. I have the burris signature rings on most of my rifles and I love them, I have never had an issue with a scope moving in the rings. You also don't have to worry about marks on the scope with these rings either.