I answer on very little sleep and just a knee-jerk reaction, but here it goes:
If you have play-tested so much, there shouldn't be that much errata. Even with the OMG books available through Lizards or Paizo, one, or TOPS, two errata updates are all you need. I wouldn't pay for monthly updates for this, as it is overboard and I would be paying for nothing.
Secondly, how would you keep it out of the hands of those of loose morals? All I have to do is pay $2 and download everything, save it to my computer, cancel my membership, then upload a torrent of it and you are getting screwed out of intellectual property.
The basic premise sounds interesting, but keep in mind that this is just a first-peek and I'm running on 45 minutes sleep over the last two days.