There is a discussion on the meaning of major / minor in the article of the Checkmating Applet for 2 vs 1 checkmates. Pretty much the same as what you say here. Note that the checkmate must be forcible from the majority of the possible positions; help-mates don't count. So the Silver General (FfW) is a minor, even though there are checkmate positions because it attacks two orthogonally adjacent squares. The Gold General van force checkmate on 8x8, but in a minority of the positions KGK is still a draw, when the bare King can attack the Gold from its 'blind side', and drive it to the edge that way. This can be seen as 'deep tactics' that lose the the piece; of course any position where a piece X is forcibly lost isn't really a K+X vs K end-game, and should be excluded from the statistics.
More tricky is the case where there is a fortress draw. such as with the Dragon Fly vRsD on 8x8. There is a 'safe edge' there which the piece cannot cover. If the bare King can reach that, the game is a draw, even though you still have the Dragon Fly. If you can cut off the bare King from that edge, you can force checkmate. So this is an intermediate case ('medior'?).
I tend to use the term 'super-piece' for Queen-class pieces.
There is a discussion on the meaning of major / minor in the article of the Checkmating Applet for 2 vs 1 checkmates. Pretty much the same as what you say here. Note that the checkmate must be forcible from the majority of the possible positions; help-mates don't count. So the Silver General (FfW) is a minor, even though there are checkmate positions because it attacks two orthogonally adjacent squares. The Gold General van force checkmate on 8x8, but in a minority of the positions KGK is still a draw, when the bare King can attack the Gold from its 'blind side', and drive it to the edge that way. This can be seen as 'deep tactics' that lose the the piece; of course any position where a piece X is forcibly lost isn't really a K+X vs K end-game, and should be excluded from the statistics.
More tricky is the case where there is a fortress draw. such as with the Dragon Fly vRsD on 8x8. There is a 'safe edge' there which the piece cannot cover. If the bare King can reach that, the game is a draw, even though you still have the Dragon Fly. If you can cut off the bare King from that edge, you can force checkmate. So this is an intermediate case ('medior'?).
I tend to use the term 'super-piece' for Queen-class pieces.