Third edge in the middle is Elan and it doesn't really do much! the UT's have a second edge about 3/4" in from the outer running about 1/3 the length of the ski underfoot. it's also got a di cut material surrounding that inside edge that is harder than the other base material. Edges crack and break on ALL skis, it's the nature of our sport. What these re-enforced edges do is help distribute the impact of landing on a rail over a larger metal surface area, what this does is decreases the frequency and severity of cracking edges.
I've read on NS that some of you have blown these edges and cracked them all over, I find that a little hard to believe since I'm 205lbs and had no real troubles with mine after about 60 days on them last year, a couple small cracks but that's it.
Either way, if anyone has any questions about Atomic or their Product feel free to PM me, I'd love to help.