I agree that the FAQ information is inaccurate and misleading. I wasted a lot of time looking through the FAQ for these names. I was aware of the information you reported, but couldn’t remember the names. It isn’t easy to find it in a search. Unless you know to search for Winbond or ST Microelectronics you probably won’t find it. And if you already know these names, you don’t need the search.
Although the firmware is interchangable, I wonder if the firmware originally designed for an EPROM might not have some benefit. This is based on some user reports of less errors with the 48125S firmware. I just reflashed my (originally 40125S) 48125W to a 48125S to check this out, but haven’t burned anything yet.