I can add that, except in the late end-game, it is extremely rare you would be allowed to promote and survive. The opponent will almost always sacrifice a minor to prevent promotion or capture the resulting piece on the promotion square. So it doesn't matter very much what is available as promotion choice; you will gain a minor for a Pawn when you can force a Pawn into the promotion zone. So you don't suffer very much if a minor is the only piece available as promotion choice. It is just that the opponent gets the choice not to trade his minor for it.
So the promote-to-lost-only rule doesn't affect the game that much. The most notable effect is that in a late end-game where there still is a super-piece and an unobstructed promotion is possible, you will have to pick a different super-piece. But since there are three nearly equivalent super-pieces, each giving an advantage so large that the game ceases to be a serious contest, that doesn't make much difference.
I can add that, except in the late end-game, it is extremely rare you would be allowed to promote and survive. The opponent will almost always sacrifice a minor to prevent promotion or capture the resulting piece on the promotion square. So it doesn't matter very much what is available as promotion choice; you will gain a minor for a Pawn when you can force a Pawn into the promotion zone. So you don't suffer very much if a minor is the only piece available as promotion choice. It is just that the opponent gets the choice not to trade his minor for it.
So the promote-to-lost-only rule doesn't affect the game that much. The most notable effect is that in a late end-game where there still is a super-piece and an unobstructed promotion is possible, you will have to pick a different super-piece. But since there are three nearly equivalent super-pieces, each giving an advantage so large that the game ceases to be a serious contest, that doesn't make much difference.