Svend....If you're working on improving carving skills, I still like as the primary ski a ski in the 64-68 mm waist.
Jim stated it very succinctly...nice job!
A ski in the 70-80's underfoot requires less technical attention when skiing broken piles of snow and deep powder. I do think if one does not pay attention to the turning radius of a mid-fat, that ski could FEEL cumbersome when skiing the groomers. Jim points out issues on bringing the ski up on edge. A proficient skier that knows how to create angles, using tipping of the skis through their ankles already understands these skills and would have no problem with the transition to a wider ski. But not everyone is a technically proficient skier...but then there's the fun factor and many people love these mid-fats cause they don't have to be as technically correct and the rider can have more fun on the mountain. A skier with the technical skills can certainly use a mid to fat ?2nd ski in a variety of terrain conditions cause they LOOK for those conditions to play in.
Having said this and so we don't lose focus on what your wife wants the ski for....
I think a wider under foot ski for wedging with the kids and just pushing around snow would be just the cats pajamas....and then when she wants that ski to crush piles and deep snow...she already has the skills for sure if she's piloting the Head SS Speeds.
Still sticking with my demo selections for her and hey....there may be more when the 08-09 skis show their pretty faces!
Best,
Gary