coming from a relative newb, i'm just thinking out loud...
If you are primarily mixing at home (J in your case I'm making the assumption you are keeping the amp at home and not in a mobile rig or something).
What volume do you usually mix at? I've been realizing as I do more and more, I am naturally mixing around 85dB (obviously doing spot checks & random listening it gets cranked, unless it's ns-10's and then I naturally seem to end up 6-8dB louder by the end of the day...I dunno why...I f'in hate those things...but that's that's an altogether different, beaten to death issue).
This is really more of a question...assuming you have a decent noise floor (and barring major design changes as amp power increases), if you're not worried about headroom what does the extra power give you?
It's great to say get a 4B rather than a 3B (btw I actually have an older 3B and love it) but when/how do you decide "I think I need the 20xxx rather than the 10xxx"?
A lot of times during tracking & overdubs the control room monitors are rockin, etc (this is not w/ the 3B fwiw)...but otherwise???
Just curious...
ken