Seems to me it's not a question of 'how low can you go?' - any idiot can do that until contact is eventually made. It's more a question of 'how low can you operate?'. We all know that Buccaneers operated very effectively at ultra low level. On the other hand, I well remember competing against SAC B52s with Vulcans. The Buffs were not allowed to fly below 1000ft agl as their 'normal' low level operating height and this, surprise surprise, gave them a considerable edge with radar bombing. At least they didn't bomb blue forces that way.