I've got two 6 series Madones, a 2009 model and a 2010 model and I've owned a couple of the older style Madones. I was a little concerned to read this article as I've always been a little wary of super lightweight products. I did buy a torque wrench allen key when I switched from the aluminium steerers of the old models to the new carbon steerers to ensure I wasnt overdoing things and I've always run a 5mm spacer on top of the stem. To date, no issues, despite a couple of off road excursions and hitting a few hefty pot holes hard enough to shift the handle bars forward. I did speak to my dealer about this, but he hasnt raised any concerns.
I've always found Trek to have excellent customer service and warranty replacement, so I cant see them doing this to make you buy new bikes every year. I have had one Trek frame warrantied 3 times due to paint issues.
Looking at the photos in the article, there did seem to be a lot of stack between the headtube and the stem, surely the rider would be better off with the performance fit, rather than the pro fit, which has a 2cm longer head tube.
Does this highlight another issue of riders trying to ride bikes that dont fit them properly?
Still rather concerning though, I'll be checking my steerer tubes tonight!