i have a few different helmets, but the visor doesnt distort you THAT much.
i use a "dark" tint lens all the time, and i go to work when its dark, and ride at night often. but when its really dark, and your not in "town" (like back road where headlight is all you have) it can take away , but its not like your blind.

id say jsut get a regular lens, and wear some sunglasses underneath during the sun, they are easier to store and carry.