I have a pair of Phat Luvs with AT bindings on them for backcountry. I also use these inbounds on trails, in the woods, in ungroomed bowls. They are excellent in powder, corn, spring crud, cut-up frozen snow, and so forth. They don't do well on ice or bulletproof snow, naturally, but they handle groomed pretty well, whether it's soft groomed you find out West or the firmer groomed you find in New England. I have never skied in Australia, so I can't compare our groomed to yours--but you know whether your snow is usually soft or usually firm. However, when I know I'll be confined to groomers, I switch to my carving ski. I didn't buy this ski to use on the groomers, I bought it to use in the backcountry, and inbounds when the snow is really good for off-trail skiing (do a lot of tree skiing).
If you want to avoid such a fat ski, and really want a woman's K2, I understand they are making a new Lotta Luv, which is the woman's version of the Apache Recon, for 2005/06 season. It's 78 mm underfoot, if I recall. Fatter than the Burnin' Luv, less fat than the Phat Luv.
This winter, I demoed a pair of the women's Salomon Scream 8 Pilots (dark pink color) out in Colorado. I was pretty impressed with them. They worked well on both the groomed old snow and the 2 feet of powder we got one day. They are 75 mm underfoot, I think. I will say that I would have preferred my Phat Luvs in the powder. A lot less work. I skied 4 days of thigh-deep powder on a snowcat skiing trip, and had my Phat Luvs. Honestly, we skied hard and long, and I was not tired. Not at the end of the day, and not at the end of my trip. I was very surprised!
If you already have carving skis, I suggest you go with the fat ski for backcountry. You can use your other skis inbounds if the conditions warrant. But there's something to be said for having the right ski for the backcountry, where you're going to run into all kinds of snow (except groomed) and won't have access to a stable of skis when you're in the middle of nowhere. Personally, I think you're better off to have two specialty skis--one for groomers and one for off-piste--than you are to try and find something that is good for everything but not great for anything in particular. Does that make sense? If you can only own one ski, then get the all-mountain that performs pretty well on everything. But if you already have a ski that's great for groomers, then add a ski that's great for ungroomed/backcountry.
By the way, I am 5'4", 140 lbs., fairly aggressive skier (especially when I need to be), ski a 165-170 cm ski.