There are problems with a floating D. First there is a strap you must step through to put on the saddle. To be big enough to get it on, it's kinda long. This puts the attachment point of the rope and hitch way up in the air, when most people like it down low and tight.
So then folks replace the bridge with a shorter one. But they can't get the saddle on so they use a quick link or shackle of some kind. Are they all carrying wrenches, locktite, and locknuts? No. And are quick links ANSI approved when used without locknuts? It depends on your interpretation.
And think about it, if the bridge is so short, how much sliding is going on?
Double D ring have the advantage that you can wrap the saddle on, then clip the bridge together with the ANSI approved carabiner you use to hold your split tail. All nice and low and tight.
The straps that have the D rings are often too long, so back to shortening the bridge.
What looks like the best solution to the problem is what they did with the Glide. Have not tried one though.