Basically what corst said. Oly shoes are actually fine for deadlifting less than maximal weights. Olympic lifters are doing just that. The weights they're putting above their heads are less than their max deadlifts. If you're not training for powerlifting, you could use oly shoes all the time to deadlift. They won't keep you from getting stronger.
The bar position becomes an issue only when you're lifting around 90% or more of your max. At that point, it becomes substantially more imperative that you're using correct leverages to lift to your capacity.
So for me, I could knock out a lot of reps at 400 lbs with oly shoes on, no problem. And if I was trying to get better at olympic style lifting, I would practice this regularly, to get used to pulling with less than optimal leverages to initiate the clean or snatch. If I go over about 500 lbs, I'm gonna go ahead and put on some flat shoes.