I've carried both on duty when we carried revolvers ,and I find that the Safariland are much quicker and easies to use under stress .There's no twisting or other things you have to do to release the rounds .Just line up the rounds and push .When the release button in the middle of the loader contacts the back of the extractor pin ,it just sore if throws the rounds into the cylinder .I have both but prefer the Safariland over the HKS .
Also you can get the Safariland in three diffrent types .One a duty holder with a small button on the back ,and it's even smaller than the knob on the HKS, next is a slightly larger knob type and then a very large knob for competition use .The duty ones are much easiers to carry in a pocket than A HKS
Lou