Mac Icon Formats

I’m a little confused about the ‘icns’ icon format for Macs. All of my sources say that is a valid, standard Mac icon format. Yet, the instructions on the Disney Experience say otherwise. The person who submitted the instructions says the files have to be converted with a program. But every Web site that I come across (including the site of the icon program that I use) all say that the ‘icns’ icons that I’ve been designing should work just fine. And, I’ve never had a single complaint about compatibility issues.

So, my question is this: do any of you Mac users (especially OS X) out there have any problems with my icons? Do you really have to convert them before using them? Am I using a bad format, and should switch to either ‘bin’ or ‘rsc’? Let me know of your experiences, and be sure to include which OS you’re using/have used.