I bought the Double K's with 12' cable & clipped 3 horses the first summer I had them. I like them fine, though I like them better with the Andis blades than I do with the Laube blades I got last year. However, I'm kind of regretting buying them--I paid A LOT of money for them (at the time I got them the US exchange rate was still quite high & that really adds to the price) and now they hang in a closet unused, because last year I bought a Wahl Chromado cordless (can be corded too) & I use that for all my clipping. For what I paid for the Double K's I could have had two of the Wahls, plus a few spare blades--I'm doing a lot of clipping with this set of Wahls--usually I clip dirty horses too--and they do real well for me.
When I did use my Double K's I didn't have a problem with them heating up; seems to me someone has mentioned before that if they are getting hot too quickly it's often because you're clipping at too slow a speed?