Back to the original question and I really have no problem with the spelling being changed for American publications. For me, it's much the same as translating the strip into a foreign language---you are simply catering for the market. For example, as Feather said, the use of the word "colour" in America would most likely be construed as a misspelling of "color" and it makes absolutely no sense to me to insist on the original. Language evolves constantly and I can understand completely why Americans have decided to simplify the spelling of certain words.
Diane, how do Canadians approach this? Is it "colour" or "color"?