Hi Sean,
Commiserations.
Mavericks has crashed my early/mid 2008 imac 24".
I was offered the upgrade as a free and reccomended Apple Software Update that arrived on my computer.
I stupidly assumed that Apple would not offer me an update that could harm the performance of my computer or render it useles.
Big mistake when I remember how upgrdes cooked both mine and my daughters iphone 4 mobiles leading to having get new phones.
I installed Maverick and it was running but some programs not funtioning.
I turned it off a few hours later and the next time I tried to restart the following occurred.
Grey background with apple and spinning gear visible but computer kept shutting down and trying to restart in a loop action.
Contacted Apple by phone, and, as directed, tried, but was unable to access parameter reset, safe mode, the imac wont reinstall (gets to a point where you here the installer ask about the language of choice and then freezes.)
Went to Apple Store they could see the hard drive was working but could not re install.
I was offered a $800+m repair, which I did not accept and have now escalated the issue to Apple Customer Care in Singapore.
Awaiting response by Monday on whether they will replace or repair the imac at their cost or are our old Apples being turned into Lemons by badly planned software update invitations from Apple.
