I made a 7% ROI on a conversion last week.
If we trust that the people who are setting the converstion rate are truly trying to maintain 1$ per SBD, as long is the market is undervaluing steem the peg makers will incentivize removing SBD from the market.
This is the primary function of the peg. Decreasing the supply of SBD by converting to steem is a supply side control on price. The demand side is controlled by the annual interest rate.
As $1000s of new steam dollars are currently being given to content creators every day, I think that the steem dollar price will likely be below 1$ for some time. I doubt the 10% interest rate will be enough to convince people to hold a large amount of steem dollars, especially when almost the same amount of interest can be earned in one week through conversion.
I'm actively buying SBD and converting to steem.