I don't get the 1:1 thing. It doesn't really matter what the ratio is, so long as it is a ratio that is communicated clearly and is not alterable, yes?
It could be 1:100, 1:2, or 10:1, and when you return to the MC it reverses.
don't know but i suppose he could change it and trap ppl inside.
Oh yes, (developer + miner) integrity is needed.
And there are a bajillion possible scams with new block chains, we've seen a lot of those in alt-land, but the ratio is immaterial to that.
So... no reason it can't be 1BTC:100scBTC on the way in and 100scBTC:1BTC on the return.