In reply to Chris Beck: I've been using the same Leki twist lock poles for ski touring (and snow shoeing/staggering in to ice climbs/etc.) for the best part of two decades. They've never failed. I have though had flick lock poles ice up to the point where I needed a swiss army knife to chip away the ice to allow me to get them to work! Cheap twist locks can be utterly rubbish, but so can cheap flick locks. Twist locks by Leki or flick locks by BD both seem to work well though.
Flatt4matt: how's your skiing? I'm an ambitious telemark ski mountaineer of a dubious skill level and still using 15 year old low, soft T2 boots. This basically means I'm rough on my poles. I've snapped a pole by sort of landing on it whilst trying to jump turn in crappy snow and bash them about quite a lot. I therefore favour meaty poles for winter, and my old 2 part Lekis do that well. I want three part for summer or walking in to winter or summer climbs where I'll put the poles in my pack whilst climbing, so have different trekking poles. Nevertheless, my current BD 3 piece poles came with both summer and snow baskets and have worked fine for snow shoeing and some piste skiing this last winter, so if you are a good skier don't see why one pair wouldn't work fine.