A triple-position climbing aid gives you three heel riser heights instead of two, letting you fine-tune your lift to match the slope angle more precisely. On steep skin tracks, this means less calf fatigue and better balance, since you can choose just enough lift without going too high and feeling tippy.
For serious touring and ski mountaineering where you're tackling everything from low-angle approaches to 35-degree+ climbs, that third position really shines. You'll spend less energy fighting your own body on long uphills, which leaves more in the tank for the descent.
The trade-off is slight complexity — you have one more setting to manage, and it's another moving part. It's also easy to forget you left a riser up before skiing down, so always double-check. If your tours mostly stick to moderate terrain, dual-position is plenty. But if you're regularly hitting varied and steep skin tracks, triple is a worthwhile upgrade.