I went from a 2003 4/4 4 seater to a 2010 2 seater plus 4. I thought the 4 seater would be used as a fun family car but the number of times we went 4 up was really rare. Everyone will talk about the power but I have to say the best thing about the change was having better weather equipment and (even better) the ability to set off with roof off and side screen stored knowing if it started raining hard I could stay (almost) dry. The problem with the 4 seater was nowhere to store 4 side screens.
Minor point but you'd be surprised how many more times you set off in the Morgan. More power was fun too though !