I have had exceptional results with studding tires on off road motorcycles. It may be an apples to oranges comparison but they are subjected to very high stresses too. Frankly, I have only tried metal screws but with good results. Maybe I got lucky on my choice of screws but I didn't use self tapping and that may be the difference. I looked at the ice screws and bought the closest thing I could find for metal.
The first time I installed screws, it was late fall before our first snow fall and from the first trial run on a local trail it was immediately obvious that the studding was like the difference between 2WD and 4x4. I have never used them on a tractor but if they offer anything close to the motorcycle's improvement on ice,snow,dirt,logs,loam.hardpack soils,etc......I agree, "prepare to be amazed". I have, at times used a studded rear tire for all season riding since. I have never gotten a flat from them and I have had a few pull out but even that is rare. I also don't ever recall snapping a head off of one. Think about your pattern, you don't want to place them so there will be too few in contact to help bite. One or two small screw heads in contact at any time isn't going to do much. You want to space them around the radius of the tread in alternating rows ( for lack of a better way of saying it) so the heads aren't just digging straight lines as the tires turn. Place them so to make sure that if the tires spin that the heads will bite every surface, just like the tread itself. Yes, A "true" studded tire takes a LOT of screws....the more you use, the better results you will have. There's a lot of online info about how to do it to motorcycle and atv tires, how far you want to take that towards your tractor is up to you. These guys are looking for, and getting traction that is almost like riding on dry pavement so studding your tractor for zero tire spin like they are is probably not practical from a dollar perspective but I think you could find a happy medium with sheet metal screws.
