Hey caerlleon,
Some pretty good stuff there! I may pick up a CD!
Also, while I may not be quite as much of a Theremin fanatic as the rest of the members here, I too have had difficulty finding ensembles of Theremins. In searching, I've come across:
Mable (http://www.synthgear.com/2009/music/theremin-ensemble/)
First Theremin Orchestra of the 21st Century (http://www.youtube.com/watch?v=GjlwEuREAbI http://www.doritchrysler.com/ThOrchestra.html)
ICEM Theremin Ensemble (http://www.myspace.com/icemthereminensemble/music/playlists/icem-theremin-ensemble-s-playlist-2444969 http://vimeo.com/user1873960)
Seattle Theremin Orchestra (http://www.youtube.com/watch?v=G7EunQrHfQ4&feature=endscreen&NR=1)
Vacouver Experimental Theremin Orchestra (http://www.facebook.com/pages/Vancouver-Experimental-Theremin-Orchestra/342968222393760)
And one from my hometown (http://thereminensemble.com/)
Other than the first couple, the others seem pretty amature.
There needs to be more Theremin collaborration!!