Thanks everyone, I'm glad you like them! I, too, thought they might cross a bit into stripper-shoe territory, but in person they look much more delicate than they photograph (at least in my photos!)
They are VERY high, and the ultra-thin heel doesn't help much with balance, but practice (and more legwork at the gym) seems to help. The heel is 5-3/4 inches and the platform about 1-3/4 inches, so the actual rise is about 4 inches, or equivalent to wearing a 4-inch heel. I know the Louboutin women like Magdalena can handle that!
I got them last week at NeimanMarcus online - they had only one pair left and it was in my YSL size, so I figured it was fate