The main reason for the Alpine Butterfly as I understand, is it's ease to untie after loading. Say some sort of crevasse rescue/raising situation where there is tremendous load on the knot. I haven't seen anyone use it for a tie in near the bitter end tho. Only for a mid point knot to form a loop.

I haven't used them, prefer a double bowline since it is also easy to untie and spreads the wear on two loops of rope. The double bowline is common when building a Banshee belay anchor too.