I have a CR Speed thumb rest on my Open gun, but I got to handle a DAA the other day and that definitely seems like the way to go. Especially on a Limited gun that doesn't have a scope mount, you'll want the built-in shield that the DAA has so you don't stop the slide with your thumb.
Off topic, is that one of the new STI aluminum grips?
It is an STI aluminum grip but I believe it is the old style that Matt Fitted. It was anodized black.
Thanks Jeff