I'm a bass clarinet player. I double (kindasorta, occasionally) on soprano. i've also played contrabass in clarinet choir, and messed around on a contra alto, alto, and Eb (just borrowed them from friends who play them, never actually played them in a piece)
I've played Bb soprano since 6th grade (I'm in 9th now), and last week I started playing the alto so I could play it in District Band. I also play the alto sax, so the transition wasn't too bad. But I haven't done anything too major on the alto clarinet yet, mainly just messing around and practicing scales.