I think that you are correct Cosmo.
I had another look at your photos and a read of the books and I now concede that you were most likely limited by the high speed buffet margin. My mistake was in thinking that if you were, your selected speed would have been coincident with the bottom of the upper amber band which it probably would have been if you had climbed the extra 300ft to max. My apologies.
A question for you for my own learning;
If you were at max altitude and the selected speed was below the upper amber band, how would you know which of the three thrust based limitations were ' active' so to speak?
The holding speed is calculated that you are actually able to do turns in the holding.
can you provide a reference for that because the JTPM written by Boeing has lead me to believe that BEST SPEED is nothing more than the speed at which the engines would have the minimum rate of fuel flow and can be a speed well below min drag. Seeing as Max alt is sometimes limited by the ability of the engines to power you through a 15 degree banked turn I can't see how that speed would allow 15 degrees with the extra drag of being below min drag.
And like latetonite, I select CON when I need to. And I do so routinely due to the way I operate the aircraft (de facto's objection against routinely, was what got me involved in this thread, although it is completely in line with the recommendations from Boeing).
I have no argument with this practice but can see why pilots coming off other Boeings might, in some Max Con is only to be used in emergencies. If the Climb N1 and the Max Con N1 are the same there is no restriction and that applies to the NG.