I honestly didn’t even think of the beer when I saw your post. It’s a beautiful name!
I definitely prefer the original spelling of [name]Cillian[/name].
[name]Both[/name] spellings are OK with me. I do agree that people would more likely mispronounce [name]Cillian[/name] and that [name]Killian[/name] spells “Kill” in it but, honestly, I don’t have a problem with it.
It could be because I love the name so much that I just put the negative connotations aside.
If I had to decide on spelling right now, I would probably go with [name]Cillian[/name].
Good luck!