In reply to florence58: I use BD Seracs at the moment with my Trango Extremes and they fit very well - especially in the smaller sizes (I've got EU40s) I found the Sportiva heel fits the BD crampons better than similar Grivels, which seemed at the time to be designed for a slightly wider boot.
I've had a play with some Trango Alps in a shop and they do take a C2 semi-auto very well.