I've been fishing circle hooks for a long time now. While occasinally a really aggressive fish will suck the fly in so hard as to get it wedged behind a gill, causing potentially mortal damage, those are very few and far between and the vast majority are hooked either square in the corner of the mouth or in the upper lip. Having said that, I've never used them on speckled trout before. My experience with traditional j-hooks on warmwater fish was that they got hooked deeply far more often, though still leaving a fairly small number of fish "mortally" hooked. Just my experience for what it's worth.