...pronunciation guide, I suspect, is perhaps not the most authoritative, anyhow.
Funny, but we had a small debate about the pronunciation of another name over on another names discussion board, and one person used babynamer.com as the authority for the pronunciation of the name in question. In that instance, I was in disagreement with babynamer.com.
Yep, Merriment, "may-gen" is how the name is generally pronounced here in the States. Doesn't mean we Yanks got it right, though. ;)