indoor unicycle

I'm thinking of buying a unicycle for indoor use, as the two I've got at
the moment (Coker and 26in Muni with big tyre & metal pedals) aren't
really suitable and I'd like to get along to some of these unicycley
meets and stuff. Anyway, I was looking at the DM ringmasters because they
seem to be pretty good from what I've heard. Anyone know if the advanced
version is worth it, or is the standard one going to survive okay? Also,
what wheel size should I get? I'm going to try and get along to the
London hockey things soonish, so the size most people play hockey on is
probably sensible.

cheers,

Joe