Just to join the thread with my recent modded '66 'stang. I'll be hoovering up all the posts here later as a recent Short Scale pilot. To be honest, I love the Mustang but I don't really notice the different scale that much - I've always used light strings so the tension is familiar, and the bass sounds very similar to my full scale P. The size is really convenient and I love miniaturisation so I love it to bits, but it feels completely natural and not that different practically to a full scale.
I'm changing the controls (vol/vol) to balance/tone soon. I think the shorter scale does accentuate the different hand positions and pickup blends - small change shave a big effect. I didn't expect one of my fave sounds being to use the top thumb rest and play on the end of the neck. Fave overall though is P pickup with 50% of the Jazz, digging in and letting the notes rasp - it sounds really fruity.
I've been playing it and looking at it so much these last few days that the shape just seems 'right' to me visually. 'Normal' basses look awkward now. Before, I thought Mustangs looked awkward. Weird.