Oh, I've used them. I just used them on a couple of small areas of my last project. Only a couple spots though. I disagree that spirals are the only way to get fine detail on fretwork.
I've done mountains of fretwork and there is no way to get as fine and sharp of a cut as you can with the finer regular blades. Flying Dutchman from Mikes of course
A round blade just isn't as thin as a fine regular blade.
Now that doesn't mean that some of the most beautiful work isn't done with spirals, but it can be a different look up close. Sort of like the difference between styles of artist brushes in a painting.
Actually, when I want really fine cuts, I like Mike's Superior Puzzle blades. Those are my go to for really fine cuts. I have a couple of Mikes spirals. The "New Spirals" and the spirals with flat ends. Nice blades.
Ray