Hmm, I can see the benefit of only paying for the time you spend playing, especially if you don't play so much, but something about it just feels like a bad deal. But it's not, is it? Almost three days /played for $5 is pretty good. You could play two hours a day (every day) for a month with that amount of time.
Meh, I need more coffee before this makes sense, I think. Definitely need more sleep before I get more coffee, though.