Whatever you buy, make sure it is from your local dealer, and have a serious talk with them about support! Most of us on this site work on them, so local support is not so important.
All of the things I've done are tuning, adjustments, upgrades, and fixing flats, etc. Mine has a carburetor, no EFI, and mechanically it has been excellent. But some people have EFI gremlins or mechanical failures that they deal with on their own with some guidance or suggestions from these folks. You really need to be able to trailer (or drive it) it to a dealership in a pinch. Yes, you will find people having EFI problems, even on the KPX in threads on this site (you should know- full disclosure
). Rare perhaps, but we don't actually have numbers so it's unknown.