BriPhil says:
While OS X is inherently much more secure than the-operating-system-that-shall-not-be-named, the only truly invulnerable computer is one that is BOTH air-gapped (not connected to anything else) AND completely shut down. Viruses that target the Mac platform are relatively rare at the moment, and they're generally not able to do as much damage for now, but both of those circumstances are beginning to change as Apple's market share continues to increase.
If you're very disciplined in your browsing and e-mail habits, your Mac can (probably) survive a bit longer without protection
... and i wholeheartedly agree with both. Sadly, the first is correct, we have been safe only because we have not been worth targeting. now we are.
Happily, the second remains true too. Avoid dubious sites, never say "ok" to anything, set OS X to ask for permission before instilling anything, don't follow suspect email links, and you will be safe 99.something % of the time.
I have yet to see active security software that was not trouble - on either platform. A check, like Malware bytes, that you run, is typically innocuous.
And i just updated my 3rd machine to X.11.2 with no issues, and am typing this on it. As to mail, i have a gaggle of IMAP accounts.
Grant
ps: strangely, firefox only showed the first 4 pages of this thread. Safari shows them all.