These "features" are extra keys and some software functionality like macros. Neither of those adds anything significant to the manufacturer's cost and you can get them on mechanical keyboards like BlackWidow. The Logitech "gaming" keyboards are simply extremely overpriced, repackaged versions of their cheap stuff.
---------- Post added 2011-06-08 at 06:15 AM ----------
I have never had any keyboard or mouse of any manufacturer break. What I'm talking about is deterioration which happens to ALL cheap membrane keyboards including your G15, if it doesn't bother you then great but it's hugely noticeable if you've ever compared it to an actually proper mechanical keyboard.