Yep, just upgraded mine to Mavericks and had absolutely no issues. You just need to make sure you buy components that are tried and tested by the hackintosh community.

How often have you had to re-install the boot loader and/or kexts? Each time you upgrade OS X, sometimes, or never?

Never. To upgrade to Mavericks I just created a USB installer using unibeast, booted from USB and followed the usual OSX install process. All my files and apps were left untouched.