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I have done computer measurements of the piece values of the divergent combinations of Q and N and K and N in a FIDE context. The results supported an earlier observation, that a 'Lion' (Betza WFADN) would lose about twice as much value by disabling one of its capture moves (e.g. fW) as it would from disabling the corresponding non-capture. The value of mNcQ was around 7, that of mQcN around 5 (so 2/3 and 1/3 on the way between N and Q, respectively).

The results for the K+N chimera was more surprising. Here we start with pieces thatare already very close in value, so that the interpolation does not do much, and cooperativity effects stand out more visibly. The conclusion was that a pure K (Commoner) is slightly weaker than a pure N (about 0.3 Pawn values), and that mKcN is quite close to pure N, as expected. But the surprise was mNcK, which came out about 0.5 Pawn stronger than pure N!

My speculative explanation is that there are some terms in the piece value that depend on global properties of the move pattern (rather than contributions from individual moves). Like the K value is suppressed because it is a 'slow' piece, (it cannot overtake a moving pawn), but ehanced because of 'concentration' of its capture moves (it can at the same time attack a Pawn, the square in front of it, and the Pawn that protects it). The mNcK has the best of both: concentration of the capture moves, and speed of the Knight.