I suppose if you were pushing snow over pavement or doing lots of grading with the bucket you would appreciate the reversible and replaceable lip.
Anyway, I noticed the holes straight away and initial thought was they were for bolt on individual teeth. But if you look at that edge, it doesn't look beefy enough to hold up to that if you were doing some tough digging or going after some roots. For lighter duty buckets you need those small 90 deg tabs connecting with sides of bucket along with the over-the-lip support. Otherwise you would mangle the bucket most likely. Depends on what you were doing and what kind of breakout or curling strength you had. I'm not an engineer - could be wrong - but from just looking at CK3510 and noticing those same holes it looked like it would be a bad idea to use them for individual teeth without some other reinforcement.
I don't know how the piranha attaches since I bought a different brand, but mine only uses 1 hole on each side of bucket to attach. Goes around the lip of bucket. So real easy to install/remove - only 2 bolts total - but seems to have enough stiffness on its own to work hard and not risk deforming the bucket flatness at the lip. I could see a different design using those holes and not needing to go around the lip, but would still need the small extensions bolted to sides to hold up to any kind of curling motion with the teeth engaged in something tough.
