FH
'changing the MAC setting at this point should be done with caution'
I'm afraid I can't follow your banter, Frosty old bean. I don't understand how you can change the MAC setting after loading and prior to pushback. If that's the way the bird is loaded - that's it, and the MAC on the final loadsheet isn't going to change unless you rearrange the load distribution somehow. If the crew have calculated a TOPL based on an assumed MAC that turns out not to be correct then they either have to redistribute the load or work out a lower TOPL for the actual MAC.
I get the impression that we both agree on the fundamentals but I think I'm misinterpreting/misunderstanding bits of your posts. If that's the case then I apologise for restating the obvious.
E