Reporting back... We had a great week :)
Things they could influence were brilliant - lovely nannies, good ski instructor for dd1, great food, comfy rooms, handy to have a bus to get about on the days when we didn't want to ski all day. Good ski guiding - always an easy group and a hardcore group depending on your mood. AT and Sue were very entertaining hosts in the evening, and helped oil the wheels between people who'd not met before.
Things they couldn't influence were also mostly fab - we had blue skies every single day, pistes were quiet (especially n the Swiss side of the resort) as the school holidays were mostly over, snow had been amazing up til now so pistes in great condition. Also lovely fellow guests :) They're n a beautiful location, the village is very charming and there's a ski bus stop at the end of the drive if you want to potter into town on a day off.
Only down sides; dd1 didn't have a little ski buddy so found the class a bit intense and tired easily. Also the location of the ski nursery was in the shade first thing so very cold, perhaps if they'd gone out a bit later it would have been warmer. It was a bit of a pain being tied to the group if you wanted to ski at different times/places - eg knocking off early. Usually there was someone around to do a pick up but could be a bit of a faff, less easy than ski-in-ski-out. But the rest of the pluses definitely made up for that.
One of the families we were there with were on their 6th year back, which is pretty impressive, and they're booked up for half term weeks up to 2015.