Regarding George's comment, I'm considering overall strength by
piece-type. EG would value the Queen similarly whether there is one, two
or eight Queens on the Board. I think one Queen is better for Chess and
two Queens would be better for Cavalier Chess, because they better match
the overall strengths of 2 Rooks, 8 Pawns, 2 Bishops and 2 Knights in the
former case, and of 2 Marshals, 2 Cardinals, 2 Nightriders and 8
Cavaliers in the latter case.
On 10x10 or even 12x8 (without a hole), a Bishop is significantly
stronger than a Knight -- the Omega Chess pages suggest Q=12, R=6, B=4,
C=4, W=4, N=2(.5) -- and a third (Pocket?) Knight would make sense. (Of
course, I didn't follow my own advice on ClB, but there were other pieces
to drop, and the armies were strong enough, an argument which makes some
sense for Cavalier Chess too, but that Queen/Marshall or Queen/Cardinal
disparity still bothers me.) A third Nightrider for Cavalier Chess on a
9x8 Board would also be mathematically consistent, but maybe two
Nightriders exert enough influence on the nervous systems of the players,
like one Coordinator in Ultima/Maxima.