I can only second the warranty comment by greenlander.
A few years back I bought 2 X7 masts which both broke within about a week. Both got replaced no questions asked... haven't had any problems since then.
I haven't tried the X6 Skinny yet. I did try the X9 last year and found it too soft for my weight. However, a buddy of mine has one and he loves it. I am hoping to get hold of an X6 soon so I can try one.