The mju I was the last design that Yoshihisa Maitani was on. It's another masterpiece design, in my opinion. Despite being so small, it is still ergonomic. (not really the case with the XA, in my opinion) The mju II was designed after Maitani had retired.
https://en.wikipedia.org/wiki/Yoshihisa_Maitani
Worth noting is that underhand is the way to go, but one has to be careful not to push the clamshell due to gravity, as it will shut off the camera and you mightn't notice until you press the button and nothing happens, missing the moment. It's a two-handed operation to avoid this. Once you get used to it, it's fine.
I like the overhand method with manual focus cameras. Also worth noting (but doesn't apply to the mju) is that most P&S cameras have the flash on the left side, so if it is shot overhand, the flash will be on the bottom, resulting in bad shadows for flash shots. P&S should almost ALL be shot underhand vertical for this reason. Just develop the habit.
Interesting!