In 92 (I believe) we had both front hills blow out-one was a knee and the other was something else. We moved the C1 and C2 up to A team.
They rolled, then had a reroll shortly after, and still won. I believe this was the order.
I also can categorically say that Spirit would not have swapped teams: in '96 Spirit spun on A. B team rolled as is, and took second. in '95 we could have scratched our A1 for our faster C1 (who inexplicably decided to finally push, rather than just matching the A up the hill). That bit was the margin that cost us the victory and we knew it was a possibility when we started.
I don't call it unsportsmanlike for the other teams, but it seems unsportsmanlike for the B team. I'd be pissed if I lost my spot because A couldn't get through the chute. I do think it skews the seedings, so unless a valid reason could be given I do think that a limit of 3 would be sufficient (and more could be allowed with Sweepstakes discretion).