I think the problem with the way Heavy Bombers were is the fact you could score 2 hits from one attacking unit.  There is nothing else that can roll two dice and get two possible kills, except the AA gun first round shot but lets ignore that for now.
I think that is why Heavy Bombers were so powerful, you could take 4 heavy bombers and possibly kill up to 8 units, and at max you could lose all 4 bombers.  Heavy bombers were deciding factors in huge naval battles between Japan and the U.S. in most of my games with my family members.  Stategic bombing was a big deal because of the possible 12 damage from each bomber, but the limiting factors to how much damage an IC could take, the improved industry tech, and AA gun fire helped even that out.
If this is how the new Heavy bombers will work I will truely miss the old way, but I think I can live with the new rule change for the tech.