I was induced to specify and buy Lapeyre stairs for industrial purpose. What a terrible mistake. No one had one good thing to say about them. You cannot carry anything up the stairs. Mostly two hands must be used on the railings, only one hand if your are daring. You cannot reverse direction, you must going all the way up or down if you decide you want to change directions. Ship's ladders are by far easier and safer to use. They may replace vertical stairs as they also require both hands and you cannot reverse directions. At least with ship's ladders you can back down...not so with these Lapeyre stairs......a terrible gimmick design.
Pros: May meet code in some circumstances where ship's ladder does
Cons: Terrible to use and very unsafe for industrial uses.