Personally I wouldn't go smaller ever because you can get that weird toe-hanging-over-the-shoe thing, which just makes me uncomfortable...2 cents and whatnot

That's half a size smaller if I'm reading your post right. Probably okay if they're open-toed. The higher the heel the more your toes gets squeezed. Are you planning on wearing the shoes all day or for an evening/event only? What's the return policy where you're buying them?

My feet are narrow so I do this sometimes, to get a better fit in width, so they 'stick' and don't just slide out the front. If your feet are wide don't do it. And yes there is more tolerance in sandals.