Dated - you are now stirring a dark hornet's nest. You rightly describe 'the lhs of your sofa' and that is where we are both looking at this from. Whether the crew did behave to the best of their ability is not for us to judge. Nor is it really for us to even expect that they would have. Your figures actually indicate that leaving the a/p in with a similar failure at, say 550' would have been a 'perfect' solution. Put yourself now in the cockpit at 750'. Insufficient power. A windscreen full of a busy trunk road with factory buildings before it. It is going to take significant foresight to lower the nose and 'dive' at the road, lorries and cars, plus the buildings and fence, expecting the float and airspeed bleed to carry you over it. At what height do you start the 'flare'? Will the tail clear that high lorry?
Unfortunately, a decaying speed from about 140 knots at 750 feet to 108 knots at 200 feet, resulted in a severely degraded flight path angle.
- this, of course, is only true of the OVERALL FPA - the ACTUAL, from 750' to 200' was seductively 'normal' at 3 degrees. Think about that.
To decide whether to raise flaps or not, as I have said earlier, is an unknown to me. Yes, leaving the a/p in until it disconnected courted disaster. I do NOT know how I would have reacted and nor, I suspect, do you?
I would query your 'statements of fact' regarding best L/D and I don't actually think Vref has ANYTHING to do with L/D? As for 'eeking out as much distance as it potentially could" - we all know that using the last few knots of airspeed down to just above stall CAN be more beneficial than maintaining best L/D in 'stretching that glide'. The unknown variable is from what height does that work better. Neither of us know for sure.
There will be an analysis of the crew actions, certainly inside BA, and probably some lessons will be learnt. I would not presume to make that analysis. I do not think any benefit can come with these 'ifs and buts' here.