H. G. Muller wrote on Fri, Sep 16, 2016 08:38 PM UTC:
KPK would definitely be a case where you must promote to at least a Rook, and can afford to do it. If you would use Fairy-Max for piece-value testing, it would probably be better to keep Rook as the promotion choice in the entire zone. I don't expect the details of the rules to affect piece values much.
In fact Fairy-Max can be configured to use different promotion piece for white and black. This was needed for asymmetric variants like Spartan Chess. It is a bit tricky, though: white always promotes to piece #7, but if black does not have a piece #7 in its initial setup (as Fairy-Max thinks it should be, so the one given in the 3rd and 4th line of the game definition), but white has one, but black has a piece #9, it uses the latter as promotion piece for black. So you could make piece #7 and piece #8 both Bishops, and have white use #7 and black #8 for the Bishops in the initial setup. Then you can define Rook as #9. Black Pawns would then promote to Rook, and white Pawns to Bishop. You can then play many games to see how much white is handicapped by this. My guess is that it would be almost nothing.
KPK would definitely be a case where you must promote to at least a Rook, and can afford to do it. If you would use Fairy-Max for piece-value testing, it would probably be better to keep Rook as the promotion choice in the entire zone. I don't expect the details of the rules to affect piece values much.
In fact Fairy-Max can be configured to use different promotion piece for white and black. This was needed for asymmetric variants like Spartan Chess. It is a bit tricky, though: white always promotes to piece #7, but if black does not have a piece #7 in its initial setup (as Fairy-Max thinks it should be, so the one given in the 3rd and 4th line of the game definition), but white has one, but black has a piece #9, it uses the latter as promotion piece for black. So you could make piece #7 and piece #8 both Bishops, and have white use #7 and black #8 for the Bishops in the initial setup. Then you can define Rook as #9. Black Pawns would then promote to Rook, and white Pawns to Bishop. You can then play many games to see how much white is handicapped by this. My guess is that it would be almost nothing.