IMHO I think SBRs are valuable when you want to make a final push, and you want the least amount of ground forces there as possible. In general SBRs are extremely imbalanced from an economical point of view. If any AA guns hit your bombers, you immediately lose 12 IPCs worth of valuable and versatile equipment. What I think should be the rule is that if your bomber is hit, it should not be able to participate in that SBR, not get destroyed. In reality the only thing that could destroy an entire bomber wing was a fighter squadron, AA guns could not kill 150+ bombers, especially as their positions were being destroyed by the bombs themselves. Maybe to reflect this, interceptors should be able to fire at a 2 instead of a 1.