i do own 3 of the k-50's and 1-k60. i am looking for another k-60.
the k-60 has done more problem jobs than you could think of. it is light enough to carry up the ladder to the roof and snake out the 2'' to 4'' vent stack out to the root infested main. this has been my real specialty when other companies fail, or won't pull a toilet or go on the roof.
i tend to get the real sh*t calls and come out smelling like a rose
keep you eyes out on ebay. every now and then a new one can be found. stay far far away from the k-40