I'm not sure where the proper place is but I vote slider because the other ones seem too out of character for lemmings :0
The discussions are on the Engine sub-board of the NeoLemmix Bugs & Suggestions board. It's not necesserially a "only one of the four will make it" - each skill will be considered on its own merits, and the final result could be anywhere from "all four are rejected" to "all four make it in" - although based on discussions, and for the three that I've made an "alpha" implementation of (not yet released) and played around a bit with, the experience using them so far, I have a feeling about what ones might or might not make the cut. I haven't at any point (and still won't) fully said what my predictions are, though I have noted that there's at least one I'm nearly certain will make it in, and at least one I'm nearly certain won't.