yer low tunings with the 81 on a mahogany body is the only way IMO
however i still love the sound of the 81 in my basswood esp, its a bit on the bright side for the standard tunings, but you need it for c and below, esp if your in Bb tuning!
the 85 will sound a bit more natural in standard tuning in alder and ash guitars id say (retains clarity and warmth), but dont take my word too much on that! again its just my opinion