URC, I think I know where you are coming from, but to put some cred. to my statement...
Radius of turn = V(sqrd)/G x Tan theta
Where Theta = AoB
Removing constants from the equation shows that the only variables are V and AoB (in a balanced turn)
I will grant you that rate of bank change in a -8 will likely be quicker than a -400 (hence the 0.2nm fudge factor in my previous post) but the effect of this will be very limited.
AFA bank angle is concerned, you will get 25deg out of the -400, much the same as the -8 et al
Only explanation I can offer is that maybe the -8 crew is a touch more spring loaded than the -400 crew that have just done 12 hours.
(standing by for -8 crew to tell how they do 12 hour days with 5 sectors and no crew rest)
As a side note, first to admit the turbo-props are a lot more nimble with speed and altitude requests.