What issue you having with your iMac over the Windows system pls
Waking from sleep is the main one, it has just never, ever worked properly. I've done clean installs, multiple calls to Apple and it's never been fixed and drives me potty. Sometimes BT doesn't turn on when I turn the Mac on, happens more often than not, recently Lightroom performance has been plain awful, Chrome crashing/freezing, issues with TM not seeing the QNAP even though everything else on the network can, just off the top of my head.