FAH would indeed be a good choice for a 12-target leaper on a large board. In this particular case it has a bit too much overlap with the FH (Frog) and FA (Elephant) that I already have. When I used the WAD (Champion) it was as a replacement for WD (War Machine). Of course it still had overlap with the WA (Archer), but the latter is really a special-purpose piece here, because of its blocking power for flying captures. If I would have a need for upgrading another minor, the FAH would certainly be a prime candidate as a replacement for the Elephant or Frog.
Having two copies of most super-pieces really unbalances the piece-value spectrum a bit. So perhaps an 18x18 variant should have more 12-target leapers. On these large boards the leapers get weaker compared to the sliders, and consequently slider-leaper compounds also start to lag behind pure sliders. E.g. the difference between Marshall or Archbishop on the one hand and Queen on the other increases with board size. In particular pieces with 8 sliding directions become very strong, and Griffon and Rhino also belong in that class. So perhaps I should not have two Queens and two Griffons, and introduce another pair of rook-class pieces instead. A sliding version of the FAH (BH) might also be a good choice, to stay on the high-value side of the Rook. (The 12-target leapers also suffer from the large board, compared to sliders.)
FAH would indeed be a good choice for a 12-target leaper on a large board. In this particular case it has a bit too much overlap with the FH (Frog) and FA (Elephant) that I already have. When I used the WAD (Champion) it was as a replacement for WD (War Machine). Of course it still had overlap with the WA (Archer), but the latter is really a special-purpose piece here, because of its blocking power for flying captures. If I would have a need for upgrading another minor, the FAH would certainly be a prime candidate as a replacement for the Elephant or Frog.
Having two copies of most super-pieces really unbalances the piece-value spectrum a bit. So perhaps an 18x18 variant should have more 12-target leapers. On these large boards the leapers get weaker compared to the sliders, and consequently slider-leaper compounds also start to lag behind pure sliders. E.g. the difference between Marshall or Archbishop on the one hand and Queen on the other increases with board size. In particular pieces with 8 sliding directions become very strong, and Griffon and Rhino also belong in that class. So perhaps I should not have two Queens and two Griffons, and introduce another pair of rook-class pieces instead. A sliding version of the FAH (BH) might also be a good choice, to stay on the high-value side of the Rook. (The 12-target leapers also suffer from the large board, compared to sliders.)