That's interesting and I might have to pick up a couple to try. However,I can't imagine they would significantly speed up the loading process and I'm guessing they might actually slow it down because one can nearly drop a round in if it is loose with the loading gate acting as a funnel. With this it is going to have to be inserted and then the loader has to be stripped away before the cartridge can drop.
Also, it appears it would limit a Ruger to five rounds so would only work for SAA or clone. Anyway, if I had a Colt SAA and was reloading in a fight, I would want to reload it with six full up because I'm gonna be firing that sixth round in very short order anyway. Is loading six dangerous? At that point I would want it to be dangerous and don't want to give rounds away.
I continue to believe the best plan to use a single action for defense is to try to make those first shots count and, if possible, have a second single action close at hand, if needed. If you have to fight off hordes of zombies or ninjas by yourself with a single-action revolver, it is probably going to be a bad day.
Use It Up, Wear It Out,
Make It Do, Or Do Without