Nephron,
The most influencial factor is cost and availability of parts - factory or aftermarket. Lack of supportive dealers is also a factor.
While the 'bergs are much more 'polished' than they were years ago, they still have some areas where fit and finish could be improved; no major flaws, just could be a bit better.
Also, the seating position is a bit cramped for me, and I'm only 5'9"; although my buddy loves to borrow one of my 'bergs and he's over 6' and has no complaints. Go figure:think
Other things that I dislike about the 'bergs:
1. Oil capacity - you MUST change the oil after every ride as the engine and trans share less than a qt. of oil.
2. Air filter/s - in order to access the filter or filters you must remove the seat, tank, and on the FX/FE models a little shield for the second filter.
3. Valvetrain design - the design of the factory cam/rocker cover makes it extremely difficult to get a feeler gauge in between the tappet and the valve stem to set the lash. As the factory valves stretch with use, this can be a frequent pain in the butt. Replacing the valves with aftermarket SS valves solves the stretching problem, but it's still a pain to adjust the lash, just not as frequent of a pain.
4. Fork seals - I cannot remember the number of times I've had to replace the fork seals on my 'bergs. It seems like twice a year for each bike. This could just be a problem with the way I wash the bike, but after the first few times I've been extremely careful to clean under the dust seals and check the fork tubes for nicks or scratches. When I've had the forks serviced the tubes have been checked for problems and never has anything been found to be a problem; they just go through seals quickly.
Now don't get me wrong, I love my 'bergs, and the KX has it's share of little issues as well; the exhaust pipe frame-mounts and ever-loosening bolts, just to start with. But for the type of riding that I do - desert/trails in SoCal - the KX is a better bike...FOR ME.
Although, on the top-end, either of my 'bergs will smoke almost any stock geared KX any day of the week and in any terrain. My lightly modified FX600 will pass it at mid throttle in 5th and still have 6th. My heavily modified FC501will almost keep up through the gears, will pass it at full throttle in 5th, and still have 6th gear. Just a gearing issue, I know. But changing the sprockets on my KX would remove the acceleration advantage that the KX boldly displays to most other bikes.
The 'bergs are also much more stable at speed than the KX. I have always used a Scotts Dampener on the 'bergs and move it to the KX when I ride it. Even without the dampener the 'bergs feel comfortable at speeds I would fear to go on the KX without a dampener.
I'll be happy to answer any other questions, but I feel like I'm rambling on and on.
Later,
GHunter