I've seen Kirkey full-containment seats, but haven't used one. They look pretty cool. When I first started racing, I had a Kirkey seat that hugged my ribs. It worked great, but I was told I put my ribs at rish if an accident happened. I never tested that theory.
One thing I like about the Race-Tech seat is how "narrow" the head area is; I like to put my HANS on after getting in the car, and I find that I can only fit one hand between the seat side-wings and my helmet, so I need to attach one HANS tether at a time. Kind of a PITA. BUT, I feel that this lack of room also makes the seat safer if you get into an accident and your heads is thrown sideways...there's not much room to move.