I’ve tried everything on my Chota STL’s.
Anything that is purpose made of hardened steel (Chota STL, Kold Cutter, Gold Ice Screws, Goat Head) bite like nobody’s business when new BUT when worn down they all suck, which means you have to keep an eye on them and replace as necessary.
They are also so sharp (except the Goat Head) when new they can cut a fly line clean in half if you step on your line by accident…
…don’t ask how I know…
Hardware store screws work for less time and don’t bite as well but they are cheap, especially if you buy them on eBay.
Carbide studs bite almost as well and wear great; however, they are slippery as hell on very hard smooth rocks, especially rock with a high quartz content. They can also chip or the carbide can fall out or break off which means you will have to replace them eventually.
Bottom line, you can save money or your arse initially but if you just “screw ‘em and forget ‘em”, (pardon the pun), you may be disappointed in any stud.
For the last several years I have been using the Orvis PosiGrip carbide studs because of the design and for longevity reasons. I like them a lot except in places where I don’t like carbide. At those places I wear plain felt OR a combination of studs in the same shoe.
For example, at one particular creek I fish where even the carbide tip of my Folstaf skates off the huge rocks and ANY stud almost guarantees a fall…
…don’t ask how I know…
I have been taking the Orvis PosiGrip carbide studs and swapping them with hardware store ½” #8 hex head ALUMINUM sheet metal screws. Of course, the aluminum wears out fast but I buy them by the 100’s on eBay on the cheap and they bite like nothing else.
At other places where carbide is OK but not ideal, I swap SOME of the Orvis PosiGrip carbide studs with Kold Cutter, Goat Head or Chota STL's which don't slip as badly as carbide on really hard rock, or aluminum if I want to be sure.
I value not falling more than time or money so I always have several kinds of studs (hardened, stainless, carbide, aluminum) and a ¼” nut driver with me in my wader bag. If I am fishing unfamiliar waters or familiar spots where my regular carbide studs may not be the best choice, it is worth the 180 seconds it takes to swap out a few studs to get the maximum grip.