Well....
Whatever solution is used must be:
- cheap
- plentiful
- easy (relatively) to implement
- easy (relatively) to repair
- long (relatively) lasting
The question as to how to improve the adhesion of metal wheels to metal track is not just a model train exercise. Indeed, actual train manufacturers and railroads have been dealing with this concept for, oh, a couple of hundred years give or take. In the toy train realm, out options are somewhat more limited. We can't use massive weight, and we can't use sand, so what else sticks to metal rails better than soft rubber? It's malleable, it's relatively inexpensive, and it works. Bullfrog Snot is simply a variation on the design and compound. Magnets? Perhaps, but it would all depend on the implementation - I don't see anyone rushing to that bandwagon, and it's been with us for a while.
For many of us pulling short trains across level layouts, traction tires probably aren't even necessary. For the rest, traction tires are cheap and easy enough... OK, so in some cases they are NOT easy enough.... I don't really like them either, but short of soft rubber rails, I'm not sure how you impact adhesion enough to make much of a difference. Perhaps some sort of chemical coating that you spray on either the track or the wheels?
