About 2 weeks ago i downgraded my iMac 2008 back to SL, couldn't handle the laggy videos/animations. My MPB ran better than my iMac, but my charger would occasionally stop working. At first I thought it was my charger, so I replaced it - the new one was also not behaving correctly (light would go on and off, randomly). So I downgraded to SL - the charger works as designed. Finally, kids started to complain about netflix - how movies stop in the middle on their mini. I started playing around and they were right - wifi was dropping constantly. So I downgraded to SL - and the mini now works. I hope they fix these issues, I don't want to even consider a windows machine when I upgrade.