I've driven the M3W around the Western Cape. No other car receives such a reaction fr attention and there the weather is absolutely perfect - what's not to like? I think SBM's comments on what it's like when it's wet are very valid and pertinent if you intend t to replace the 4/4 rather than have as well as when you can then choose which cared pending on the weather. I always thought my 4/4 gave the most 'sensible' balance of individuality, fun, sale and cheapness to run.
Probably best to hire an M3W on a horrible day and then you'd see whether it works for you or not.