i know this is an old posting, but i thought i'd share my experiences with the microkontrol too
i first bought the nanoseries and broke too many piano keys on the nanokey (yet the nanokontrol is good) so i resorted to stepping back in time and buying the older korg, wanting a more rigid piano (and the nanoseries was great for small places, but...). nano posting: viewtopic.php?f=7&t=4189
everything works fine except slider 2 mimics slider 1 at times and sometimes slider 1 continues changing on it's own after not touching it - it's programmed as a scratch controller. so i changed channels, changed CC#s, re-wrote the scene data, updated with new driver, updated the firmware, etc. yet the behavior persists.
overall, everything else is fine. however, i find the pads a bit stiff to push and the keys smaller than i expected, but the unit is durable and i know (assume) the piano keys will stay intact as i try to play like jerry lee lewis, ha! ha!
the amazing jerry lee lewis!
ps: forgot to mention that i tested using the nanoKONTROL with the microKONTROL and both work fine together (i have 5 usb ports on my laptop, nice, eh?!)
UPDATED: my material list with images & descriptions from late 1990's to 2009 - from 16mm to VJ software