Yeah, my email was wonky for a while. It occasionally just dropped messages back onto the server and I never saw them. Not sure what it's problem iwas, but I think it's done with that now.
As for retention, it can be made to not come out without a steel cable and a tractor if you want. As far as standard retention on my sheaths, I make everything other than open backed stuff capable of inverted carry through whatever you need to do with it. I carry my own knives inverted. Shoot me the specs on the knife to my email again and I'll get you a price.
To all others waiting on a reply, a PM, or an email I've been out. I'll get back to everyone over the weekend.