Re:
Gary Klein began making bicycle frames in the early 70's and production models in the mid 70's. Cannondale made backpacks and camping bags until it decided to get into bicycle manufacturing in 1983. Comparing catalog specs, Klein geometry is different, the dropouts are definitely very different, Klein offered a lifetime warranty on the frame while Cannondale offered a trade-in/exchange program requiring $150 plus the damaged frame, etc. The Durethane enamel that Klein used for all of its paint jobs cost $1,800 per gallon (see Klein Bikes on Wikipedia). The first Cannondale bikes (ST500 road or SM 500 mountain) did NOT have internal cable routing as the OP claims nor did any of the later Cannondale's = Klein had a patent on it. And if you compare the weights for similarly sized bikes there's quite a bit of a weight difference that suggests Klein's butted tubes were different than Cannondale's straight gauge tubes. Cannondale made a very nice, well built bike but I wouldn't go so far that a Klein is a Cannondale twin with a nicer shade of lipstick.