For Rrog above, I had the SCIII many years ago at home, and used to sell Dunlavy back in the day - the 'III is missing the bass foundation that the 'IV has in spades...actually, except for being too tall, the 'III meets the OP's criteria right down the line.
But I doubt you'd find them satisfying, having grown accustomed to the more full-range sound of the 'IV.
But I doubt you'd find them satisfying, having grown accustomed to the more full-range sound of the 'IV.