Weiner won't, as AMC wanted, have to cut cast members to save money, and a compromise was reached on AMC's request to cut each episode from 47 to 45 minutes, for more commercials: the season premiere and finale will still be 47 minutes; all other episodes will be 45 minutes on AMC and 47 minutes when released to on-demand streaming and DVD. Presumably to protect the value of those extra two minutes of prime-time commercials, episodes will be released to VOD eight days after they air.
Nielsen has Mad Men at less than three million viewers when it airs on AMC, though that number increases by more than half when you factor in DVR viewership. Is it biased to suggest that Mad Men is also one of those show's that's especially popular among people who don't get cable? I wonder.
Hard numbers on downloads via the iTunes store are hard to come by, unless they are and I'm an idiot, but TV viewership on mobile devices is growing, and trends seem to be moving towards making TV available on-demand or on streaming sites like Hulu.
To make second-class viewers out of people who prefer to watch Mad Men through the iTunes store seems, to say the least, a backward-looking view—especially if, by relegating two minutes of every episode to on-demand, you're effectively encouraging a very dedicated viewership in that direction.