I haven't really talked with any other AFOLs, but if I did, I don't think I would say the acronyms at all.
When reading them, I see the word, and know what it means, but I don't pronounce it in my head. When talking about Lego, I would probably say Creations, and Adult Fan of Lego.
If I were going to say them, I'm pretty sure I would just say the letters, like A-F-O-L, etc.