I'm an eyeball engineer (if it looks right, it works better). Comparing the two hooks, I like the gradual taper from the hook eye to the body better on the F55 than I do the machined/cast (whatever) crease where the eye meets the body. My logic...a crease/fold/score is a weak point in any surface, to my EYE, the SB version has a designed failure point. (That is probably all BS, just my opinion.)
I currently have some SB made items, so I'm not gunning for SB. I look at them like I do Harbor Freight, if it's something that I'm probably going to abuse, alter or destroy, I give the HB stuff a look. For example, when I was a heavy duty mechanic, if I needed to reshape the handle on a wrench to get to a fastener, I wasn't going to cut/weld/bend a Snap-On wrench if a $5 HB wrench would do the job.
I currently have some SB made items, so I'm not gunning for SB. I look at them like I do Harbor Freight, if it's something that I'm probably going to abuse, alter or destroy, I give the HB stuff a look. For example, when I was a heavy duty mechanic, if I needed to reshape the handle on a wrench to get to a fastener, I wasn't going to cut/weld/bend a Snap-On wrench if a $5 HB wrench would do the job.