I have used BD Couloir. It's a good light weight alternative, especially if you need a harness that can be put on while having your skis on. I don't typically use it for ice climbing though. Especially when climbing multiple pitches and you need to hang on belay stance one needs a bit more padding. What comes to light weight, there's several other alternatives, you migth be intersted of:
1) Mammut has an alpine harness but it does not have quick release leg loops.
2) Edelrid has couple of interesting ones, i.e. Randonee (has quick release leg loops)and Loopo light thas gear loops which can be repositioned freely
3) Cialo does some extremely light harnesses, OZ 22 Ultra race for instance is about 82g (I'd propably end up with this one, just because it's so light)
4) Black Diamond has couple of heavier harnesses (Bod + Alpine Bod) that has quick release leg loops.
+ Each of the large harness manufacturers have light harness alternatives. I've composed a list of harnesses that came to my mind fast, you can access the list + compare the side by side here:
http://www.tribevine.com/products?open= ... 0HarnessesI guess there are few others as well.