Yes, I have. I stayed all afternoon. I order (or used to order) from them frequently. IMHO, it's the best free tour in the country. We were there during a storm and it was raining so hard that we just stayed.
One of the nicest things about Replacements, Ltd is that they allow their employees to bring their dogs to work.
I have a friend who works there. I go to a specialist in Greensboro so we stop in a few times a year when we have extra time.
My friend says it is a great place to work. IIRC Rand McNally rates it among the top 25 free attractions to see in the US.