Some companies like Blizzard use torrents for downloading updates (though you can disable it in the launcher settings IIRC).
The hurdle is that need to verify that each file isn't modified. Otherwise someone could spread game hacks by modifying the game files and sharing them. E.g. make other players the drop all their items or what else the modified client does..
The simplest solution would be to use a single singed file per torrent. However, that way users need to keep a copy for sharing after extracting the contents. In your example ~3GB occupied on the user's hard-disk space in order to safe you some traffic.
The other thing to consider is esp. for F2P you lose potential customers if the download takes too long (and users abort). So unless you are sure that enough users are sharing I wouldn't recommend it.
While I believe in testing, I doubt that the new shade of blue is solely responsible for an extra $200m a year in revenue.
Even if all the testing was done at the same time, the period with the alleged revenue increase was obviously later and during a whole year. So during that year a lot of other things including external market situations influenced the revenue change. Meaning there is no clear link between the shade of blue change and the revenue increase.
Ofc a change of blue worth $200m / year makes a better headline, even if it's rubbish talk.
I bought a PS4 first day. I really enjoy Killzone: SF and Resogun, and Flower is still great. Not much else so far and being released 2013, but I look forward to some exclusives next year.
However, if I had to decide between a XB-ONE, a PS4 and a SteamBox / PC, I'd instantly pick the last one. =)
It would be really weird to see anything but a positive reaction from a consortium which receives a substantial amount of money from Microsoft.