I have not skied them because they are hardly ever open.
I think avy gear is a good idea, though when they do open them, they are usually deemed to be "safe" from avalanches.
I'll be up there next week...we'll see what happens...though I doubt they will be open. You can ski them legally by skinning up the access road from Wilmington.
I've skied the Slides on two seperate occasions. Last year and in 2002. I believe Tony and I had a bit of a discussion about the Slides in my TR from last year.
Avy gear? I talked to someone from WF about it. The story that I was told that they will try to open it more often, however sometimes they will require Avy gear if the risk is higher. Not sure how true this is. I didn't have avy gear or helmet last year when I skied it.
I had the chance to ski the slides at the end of last season. Those slides are amazing; the closest you can get to skiing Mt-Washington with a lift. Two thumbs up!!