Yes! But I don't think there are very many sub-contrabass saxophones out there. That YouTube video (posted above in 2013) gives a good example of what it sounds like. The soprillo, in contrast, is ridiculously small (and, it appears, very hard to play in tune).
The bass saxophone documentary, linked above, is REALLY good! I watched the whole thing this morning without intending to. Some great footage of Adrian Rollini (though not playing the bass saxophone, alas).
Medjuck — your friend Josef Skvorecky is in the documentary!