Answering this question seriously, I'm a programmer / IT know-it-all, and I did it under two hours, which included firing up my own activation emulator, toward which I point my Windows. Now that I have the process down, it's taking seconds for each new Windows.
From what I can remember, there are like 10 various routines for different ways to activate different products and most of the code is just boilerplate, no? You definitely can trace the hwid codepath in a reasonable time.
if anything bad ever happened after using MAS there would be piles of evidence because MAS is brought up every time people discuss Windows license price. Equating piracy to malware is disingenuous and malware is not the only bad factor. If you consider all of them it turns out that there is a lesser chance you'll get screwed if you pirate be it music, movies or operating systems