Ism't the standard rule for IT shops "nothing from MS until the third release?" (and all that means is that the first General Availability release is really still a beta). No big deal, really, except to the hypefest that is MSM. And if you think Apple doesn't patch the daylights out of their software, you just haven't found the log file directory yet.
This seems to be more of a MS v. Linux match than an MS v. Apple, since the Feds largely use non-Apple Intel-chip machines.
Personally I have a guild-loyalty to the Unix-like microcomputer OS's: both the Free BSD kernel which underlies Mac OS X and Minux, an OS created for student exercises that Linus Torvald bootstrapped into the first version of Linux, were written by category theorists (the branch of mathematics I grew up in, though depending on who you ask I'm now considered a topologist or an algebraist). (I think a lot of category theorists feel that way--I went to a Festschrift conference for one of the noted categorists in Australia, and every laptop in the room was either a Mac or running Linux as its default OS.)
For security, the open-source model, in which every CS type, including the folks who call themselves hackers, but distinguish that from 'crackers'--the bad sort of hacker who does malicious things--get to pick over the guts of the OS, find flaws and propose fixes, is infinitely superior to the proprietary software model MS's business strategy depends on.
(I also hate the fact that virtually every default setting on MS products is the one I regard as stupid, and that the places to change the defaults are always buried several layers down in counterintuitively named menus. But that's just a matter of taste, and as the Romans used to say, "De gustibus non disputandum.")