Are the Rebel and Kiss brands a positive or a negative for the cameras that receive that label?
Outside of the Canon marketing department there probably is no answer. (And I suspect there may not be any logical answer there either.) Although they do seem to sell all they can make so it would be hard to argue for the negative. Personally, I despise the "Rebel" name on my T2i. The only thing worse, I guess, would be KISS -- hell, I'd have my acetone out getting that off the nameplate. But these names come from a culture that was wildly successful branding a line of products "Hello Kitty."
The annals of marketing are chockablock with great stories, from inane to loony, about product naming. Edsel comes first to mind. If you've never seen it, the correspondence between Ford and the poet Marianne Moore is worth reading just for the tickle. They had contracted her to suggest potential names for the Edsel. The Edsel name itself is thought to have been part of the reason for its failure. She did not suggest Edsel!
Toyota got into a long and intense legal battle with the Lexis database folks when they launched their new brand "Lexus." And I can't imagine how much money it cost to change the whole Datsun line over to Nissan; I always admired them for the courage that took.
Anyway, this is another reason I'm looking forward to the 5D3. Then I can tell people it's named for the Fifth Dimension and the camera is a hallmark of the age of Aquarius.
Okay, back to LR3. Thanks for asking.