One of the primary reasons for fishing circles for sails is because it is generally catch & release fishing, so hook placement matters. Dolphin fishing is generally meat fishing so no need to stick them in the corner of the mouth every time. Not to mention dolphin fishing is generally covering ground faster looking for debris/weedlines, whereas fishing circles for sails is more running circles around baitballs waiting for the fish to come up.
Seems like a square peg for a round hole type situation IMHO
We fish almost exclusively circle hooks, with the exception of sometimes islanders or other plastics on short riggers, and the circles have always worked very well for us hooking up mahi. I use 3/8 oz flossed to chin. Circle hook on top of the head through the X. We have tried some other methods, like circle hook through the rubber swivel. The barb of the hook should be facing the outside of the spread - free spool until the dolphin makes the 90 degree turn out of the spread, then that is the time to come tight. Adds a little more skill and excitement for us feeding the fish as opposed to just waiting on them to crush the J-hooks. Good sail hookup ratio with this method as well. We have also fed, caught, and released a Blue and several Whites this way with the dinks on flossed circles. Takes practice to get fast with it.