Crab,
How tall a cabin is your requirement? If you want something where all rear-crew can stand without stooping you are talking about a very big cabin therefore a very big aircraft. We don't need a fleet of very big SAR aircraft; you might argue that the two-type solution offers greater flexibility. How much first-aid/winch operating demands the need to be stood at full height? The AW189's spec will (if selected) bring a lot to the party, unfortunately doing star-jumps in the cabin won't be one of them. And no, I don't work for AW, just a realist.