Huzzah! Another sopranino has found a home!
I went from a tenor to a soprano to a sopranino, so the adjustment there was pretty smooth.
Well, okay, I had a lot of trouble trying to hold it while standing (because I'm too foolish to use a strap), much more trouble than with my soprano. While sitting, I rest the bottom on my right leg and hold the neck at a 45-degree angle to my left; while standing, I have to support the body with the part of my right arm between my wrist and my elbow and almost hold it horizontally against my chest. (It's actually the least awkward way for me to hold it, but I'm sure somebody else has a better method.)
The closer frets on the sopranino force me to be more precise in my finger placement on the fingerboard, and the constraints from the number of frets makes playing a little more challenging (than, say, anything with 14+ frets).
This is the only ukulele I play now. Even in an already-"eccentric" group of ukulele players, I'm an odd one out!
(Sort of. I guess. I'm still holding out for a soprano sitar-kulele.)