nabla:
1. Triple check is possible. Yet very rare in practice.

2. The rule gets very interesting in combination with rule 1. If you can only put your piece in play with a normal check, the opponent can take it off the board by promoting a pawn! :D
In my region bugchess is nearly always played with the combination of these two rulez!

rabbitoid:
If the opponent has only a king and pawns left, a promoted pawn is simply removed from the board!

Rule (2) comes often into play. Early checkmates with dropped pawns/bishops on f2/f7 can be prevented by blocking the own king. This is no beginners rule but quite an interesting defense possibility. Besides checkmating is often too easy by dropping a queen.

Two ideas for Loop-chess variation:

1. A wonderful idea would be to prevent pawns in Loop-chess from promoting normally. Instead you can pick an opponents piece on the board. The picked piece, e. g. a rook, is removed and the pawn is promoted to a rook. The opponent gets a pawn in the hand.
This brings the tactical idea of removing opposing pieces by promotion, yet carries the disadvantage of not being able to choose pieces for promotion the opponent doesn't control on the board.

2. The second idea is to prevent checkmate by Drop!
That makes good tactics more essential for attacking.

Have fun discussing this or not!