[Greg Wormald]

I like the sound (!) of the smaller room better, although you will have
to actually try to know for sure.

The 'odd' shape should be fine. I've had very good sound in such rooms.
The non-box shapes do a good job of spreading out the resonances so
nothing is too reinforced.

The overall dimensions of the small room seem pretty good, too. From my
visualisation, the speakers on the short wall could project the sound
into the room they way theatres do. Again, I suggest that with such
non-standard options you best bet is to experiment.

Greg