Also it's much easier to relaunch a foil kite in the snow than a lei,and the opposite in the water.
Foil kites are more stable through the gusty winds that blows on mountains wich makes lei to stall easier in the lulls.
Another advantage of foil kites is that you can use much smaller kite in the same wind because they have bigger surface of attack in the wind when they fly thing that makes them a lot more powerfull but with less depower than the inflatables.