I wouldn´t pay a sub for playing almost-without DM.
I would, however, pay for a sub in a Universe with monthly rewards to all playing members.
Say, 1x Free Merchant at 3:2:1, 2x Gold Detroids, 1x M.O.O.N. or similar crap all bundled up.
If I pay 5-10 bucks a month, I want a few premium items that make me convince myself it´s not wasted money, without disrupting the flow of the game.
And since everyone gets the same, no one has the advantage other than how they use what they get.