I know lots of guys who swear by circle hooks but I find that more often than I like the fish drops the bait quickly for whatever reason so I stick to octopi and just pull the trigger quickly. I don't deep hook many fish at all except the ones swimming straight back at you and think I have a very low mortality rate.
I would venture that circles would work best for larger fish more prone to just s#^^^^^&g it in and swimming away but that's just thinking out loud..
WTF!!! I am getting bashed like I'm #^^^^^^& or somthing, and I didn't even do anything!!!
Somebody just back of you while you are fishing is as bad as someone looking over your shoulder while you write a letter to your girl. ~Ernest Hemingway