Need it be either/or? (This is a possibly a naive question, but you wanted feedback!)
Could there be a 'solid' and an extended 'experimental' contract? Solid would be 'written in stone', nothing could be removed from it. Experimental would have _additions_ to the basic contract, would have scratchpad status, and be clearly marked as subject to revision, until natural selection took its course one way or the other, i.e. the extensions deprecated or included in solid. But if it's either/or, then small_to_big +1 with the reservation that things get dreamt up by pure mathematicians for their own sake that subsequently engineers make use of.
