Depends where the stretch is made, and as AC points out, what they do to the main gear. The 400 has a significantly taller gear arrangement than the rest of the family, and has a tail strike risk at approximately the same angle as the 300. The performance of the 400 is such that there is very little risk of a tail strike on rotation, and you have to be pretty ham fisted or unlucky to get one on landing as the angle is around 8-9 degrees. That's pretty nose high.