What a difficult question.
After a quick refresher, there is MAN mode & then there is 'MAN' mode.
It's a right load of old rubbish. I'll try to explain it better:-
First thing - Whenever the Auto Pilot is engaged, it always has full control of pitch & roll, the pilot never has any control through the yoke.
MAN mode simply refers to either the pitch or roll being altered through manual intervention rather than the A/P doing it automatically.
The Automatic pitch modes are 'Alt Hold' & 'G/S Auto' (and 'IAS' on the 1-11 510ED).
So the Manual pitch thumb wheels are always active except for when the A/P is using any of these automatic modes.
Similar for roll, the automatic modes are 'HDG', 'VOR/LOC' & 'G/S Auto'.
Selecting 'MAN' on the rotary switch only means that the Manual 'TURN' knob is in use for roll.
Slightly different on the 1-11 510ED - The pitch wheel only operates in 'Height Acquire' mode & there is no MANUAL TURN mode at all.
I should imagine there will be an FSX update at some point in the next two years.
There's lots wrong with it in FSX.
The way it's going, I wouldn't be surprised if a very large number of existing users stick with FS2004.
I should really wait until I've tried the final version that's now in the shops. I do remember reading that the demo didn't have all the performance optimizations that the final product had.
DM