With the 1-11 incident, my understanding is that the crew were investigating the stall with aft centre of gravity. The weights in the cabin were hydraulically powered back and forth and at the fatal stall, the engines also stalled depriving the crew of the means to move the weight forward.. .. .Whether moving the C of G forward would have had any bearing on the outcome is open to speculation.. .. .It is possible that the 727's and DC9's did not suffer from the deep stall in the same way as Tridents and 1-11's because of the high mounted tail and rear set wing. Indeed the VC10 actually developed a pitch down at the stall. I'm sure though that somebody can go into more detail.