SBRs are a great strategy. It is true that the evaluations done are too narrow and miss the overall effect on the game. You cant just look at the cost/benefit for the individual bomber. You MUST look at the big picture. Especially when the cost is affordable to the attacker, and not to the defender. On top of that, you have the secondary and more powerful effect -this is why you do this attack, of reducing enemy troop numbers in the future. Less defense means less of your valuable troops at risk. And your troops are the ones that usually have to be shuttled half way across the board before they die, so this is REALLY valuable for you (usually US or Japan).
As Allies, I go full out with the UK to bomb the crap out of Germany. And no, I do not wait until the end game either, this starts from turn one. If playing with tech, I will take the risks to get rockets, UK can afford it. Usually two or three dice a turn till I get them. Then you get a free attack. Build an extra AA and dump it into Norway soon as you can, and now you have two free attacks. This is generally better than going for heavy bombers unless you are really going to go overboard with the number of planes. Otherwise I build my bombers up to two or three and nail Germany each and every round. For the rest of UKs money, I build up a fleet of three or four trannies depending on economics and start shuttling men into Norway.
I have found this to be a very effective use of the UKs funds, and it is now up to the US to mass troop pressure on W.Eur and keep Africa clean. But with all the thumping (you can easily reduce Germany to around 20 bucks a turn by R3) from UK as well as Russia hammering their front, the US can usually crack into those sweet 6 ipc territories fairly early. Germany is simply forced to turtle, which is the absolute must have point in any KGF strategy. The US can send a bomber or two as well and really add to the pain, provided they arent using them elsewhere and are buying the necessary land troops first.
For Axis playing, I will slowly build up a bomber force with Japan and begin bleeding Russia dry as soon as those bombers arent needed elsewhere…usually by J3. Russia really, really cannot afford this and it counters the UK bombing as now UK will need to insure enough troops to defend Moscow. I dont go for tech here, the axis simply cannot afford the cash unless the allies play really poorly, in which case Rockets are sweet for the germans, but lets face it, most games you just cant waste those precious ICs like that.
At any rate, we played both classic and now revised for years in my gaming circle, and for years nobody really focused on bombing too much. It just felt too painful to lose that bomber… But now I have seen the light and I must say, an effective bombing campaign is absolutely game changing. The effect is just so profound after a few turns. The key point tho, to any SBR campaign, is to do it overwhelmingly. You cannot halfass here, you MUST bomb the living bejeezus out of the other country, or the risk is simply not worth it.