Thanks for your replys guys
SB7L - Yep, understand that Boeing have built in bank angle protection up to 40 degrees of bank (ie in level flight / constant speed) to stick shaker or buffet margin for the maneuver speed. Obviously no one wants to put this to test on the line! I also thank you for your comment re. the trend vector and understand it's concept. I am refering to an actual drop in airspeed below the up indicator with AFDS+A/T engaged, for example in a climbing turn as part of a SID. If it was maunal flight, I would simply reduce my angle of bank and pitch attitude. With AFDS+A/T in and LNAV engaged I assume the reaction is the same. The AFS is aware of min speed and wouldn't advertently attempt to fly a speed below it. The maneuver margin between the UP and the top of the yellow hockey stick is there as protection. Even entering the min speed range (never seen it happen, except in the sim) wouldn't activate the shaker, would it? At this point Minimum Speed Reversion would react. Assuming the pilot hadn't already?
Anyway, I am going beyond what I had originally asked. I feel the reason why I ask it is because some people are making mountains from mole hills!