I have no experience with the KT unit. Sturmey usually makes good stuff, but I'd find some more reviews. That Amazon review is pretty comprehensive, and written by a guy who know bikes.

Question. Have you ridden a kickback hub? If no, just FYI. When they are perfectly adjusted and maintained, and operating perfectly, they can still be a pain in the butt. Every time you apply the brakes they shift gears, whether you want to or not. That can be frustrating when you are chugging along at a good pace in high gear and tap the brake for a millisecond because you thought that dog was going to run in front of you but he didn't. When you start pedaling again you find yourself uselessly spinning like mad in low gear. Gotta kickback again to get back to high gear. The same inconvenience (but worse) occurs when you are climbing a hill or fighting a head wind and "Oops" you are in high gear. Gotta shift again which means stopping pedaling which means loss of momentum up the hill or into the wind. After a while you train yourself to "Double brake" but even that can range from inconvenient to a hassle.

Oh, and if you are like me, when coasting you mindlessly move your feet back and forth in the pedal's free space between accelerating and braking, guess what, you just shifted many times and you now have no clue what gear you are in. Pedal to find out, correct if necessary.