[scarytom]

You are correct, you cannot sell Convertible RIs on the RI Marketplace.

I think it is going too far to say that RIs are a trap: the rules are pretty transparent. I agree with you that if your infra is elastic or evolving then you need to be very cautious about making large or long-term commitments.

[vosper]

I think the convertibles are a bit of a trap, though - even though the rules are transparent. You might overprovision to begin with (which you may not realise), then you can't even sell them.