Hi there --
I have been riding KHS Brentwood since early June (nothing before that). It seems sturdy so far, but the bike has yet to take the true test of time; so far I have had no mechanical difficulties and have taken quite a few rides, including one of over 40 miles, where I kept up with the club that I was with for over two and a half hours. They were all on road bikes and their pace was 16.6mph, average. I lagged behind a bit on a couple of stretches simply because of fatigue but, definitely on the downhills the upright position is a hindrance. That and the supsension seat post/squishy seat really irritates me, but otherwise, it has been a solid bike so far. Keep in mind, I've only been riding it since June.
What type of riding do you plan on doing?