Re: OSX and Linux
"A Windows license is ~$200. A day's work for me is about $250"
A RHEL license subscription starts at $799 per year. I use Windows wherever possible. A days work for me is about $1000. Go figure...
"I'm more likely to spend at least a day of my time just waiting for the usual "Applying Updates, do not turn off" messages"
WSUS is free and manages that for you. This is a good example of why you are only worth $250 / day.
How long do you spend assessing all the security vulnerabilities for each platform? I am interrupted several times a month to look at many more Linux ones, but only once a month on Patch Tuesday to look at Windows ones...I spend far less of my time dealing with Windows updates overall.
"searching around for the exact driver, "
That's a far larger problem for Linux. based systems.
"troubleshooting obscure registry problems"
As opposed to trouble shooting problems in multiple randomly distributed text config files?
"fending off malware,"
Try running Windows and Linux based internet facing servers. The Linux ones get attacked and compromised far more often. I have never seen malware on a Windows server - only ever on a desktop. But I have seen lots of Linux based server boxes compromised to serve up malware, private FTP sites, Bit Torrent seeds, botnet CC servers, etc, etc...