warranty is only void if something breaks whilst VDC was off - nissan seems to believe they can drill that far down with their consult III when diagnosing a problem
2010 brought with it the digital mfd, so higher res, dvd playback (very easy to hack for constant playback), nav, bluetooth streaming mp3. It also has auto headlights but that's no big deal. The screen is the biggest gain in the 2010, it really is a richer higher quality unit
i have a 2010 and can use LC with any suspension setting in VDC-R mode - im not sure that's possible with the 09 model. The benefit there is you can theoretically use LC all day long in VDC-R on a stock car and still be covered under warranty. The benefit i find though is a much smoother LC in VDC-R + Comfort as it reduces my excessive wheelspin somewhat (at my power level and with lighter/less grippy 21" road tyres)