Low-cut shoes a la Sigerson Morrison

[shoesense]

I'm referring to these and their ilk:

You will recognize the work of Sigerson Morrison in these, of course--a brand that makes a LOT of such low-cut, toe-cleavage revealing, ballerinas. They're very attractive, but they strike me as sort of painful.

My question is, how do you wear these? Are they actually wearable? aren't they too tight in the vamp, across your tootsies? Won't they fly off your feet if you try to walk fast? How on earth do they stay on? So many questions!

So, does anybody have a Sigerson Morrison flat, and if so, are they comfortable at all? Any fit problems? Do tell!