I'm not an economist either, but I don't think the reverse conversion as a way to do direct peg, because it is not. It uses market forces to balance... But I don't think we truly understand how it would play out if implemented.
Besides, even the SBD is not a traditional token in a sense that the one way conversion mechanism already is not something that other currencies do.(to my knowledge anyway). It really is more like a debt issuance that has comparisons to start up funding (which I don't know anything about and am just citing the white paper for)
It is not a direct peg, but It is a mechanism that Will increase the downward force.
If implemented, the downward pressure Will be a lot bigger than the upward, wich Will drive the price down at a fast rate.
What may happen then is that the upward mechanism below 1 dollar (interest and SBD destruction) might not have a fast effect, and we may end with a Very devaluated currency.
Hard to say, really. I do think that the peg will work because the incentives are there. It is much easier to support from below in any case.
It might cause instability in steem price though, which is what I'm concerned about.