I do know of White Pines Boxers (Linda Gasper). I don't, however, know of KO Boxers and I'm pretty sure that they don't show, which makes me wonder if they do all of the appropriate health testing.
While I do believe that Linda has the best intention of our breed at heart, I always advise people (when dealing with ANY breeder) to request hard copies of the parents health testing. If the breeder ever had anything to hide, it would be pretty difficult for them to do so when dealing with hard copy proof of testing.
Honestly, I'd steer clear of Dead Broke Kennels (the link posted above). I usually don't bash other breeders on public forums (at least, I don't mention names), but I sincerely question this breeders motivations. I don't feel that they have the best interest of the breed at heart because their primary motivator seems to be money (or at least, the mention of stud prices, and "puppies for sale" right off the bat on their home page gives me this impression). They don't show, so they can't even be sure that the boxers they're producing look and act like boxers (and many of them don't compare to our standard) and there is no mention of health testing. In a breed that is plagued with many lethal (or debilitating) health conditions, I really can't stress the importance of health testing enough. No mention of take back, co-ownership or spay/neuter clauses. . . which all make me wonder if they're contributing to our shelter/rescue problems.
Worst of all, they've bred Kea FIVE times. I would likely never consider breeding a bitch more than three times (or, at least, she'd have to be a pretty darned good outstanding representative of the breed and an outstanding producer for me to consider it). Five is in line with the number of times that most puppy millers breed their bitches and I would NEVER even consider it.
Again, I'm sorry to be so blunt, but to know that kennels like this exist (let alone so close to me) really bothers me.