Gillette is actively trying to push people off of Mach 3 (and most of their advertisements specifically show people who stop using it and switch to the newest "Fusion" model)
(I'd like to see priceonomics write a blog post about the razor blade model)
http://www.theonion.com/articles/fuck-everything-were-doing-...
But they definitely push for whatever is the newest (and usually more expensive) option.