it will greatly boost adoption and on-boarding
Maybe, but I think mostly adoption follows price. If people are making a lot of money on Steemit through their posts, their friends will notice and want to join. I'm not sure viral growth math works the way you outlined it, but maybe. And I do agree, some things we should start now because they will take some time to get going, but I also think we have to be patient and think about what the big challenges will be once a viral signup growth happens. Mostly, I think, our challenge as a community will be education and helping people understand blockchains and cryptocurrency (I did some videos a while back with http://understandingblockchainfreedom.com/ for that reason).
SBD is a peg to Steem only if there is no reverse conversion. It's a broken peg. If we add a reverse conversion it should work well. There's already a PR to change the print rate.
When you say it slows the inevitable, what do you mean?
I'm not sure price will follow adoption if investors just see more users on Steem as more users coming to extract value and dump on the markets. That said, I do agree the network effect is what gives any currency value. It's a shared story. A belief. That's where all this value comes from.