Right now, I use the same general system, but with a few tweaks on the boundaries.
VPIP:
Tight: <=25%
slightly loose: 25< x <40
loose: >=40
PFR:
Passive: <10%
Agg. : >10%
Total Agg.
Same as Bison for me, but it could maybe be kicked up just a touch, say, < 0.25 at each designation.
However, I've become increasingly dissatisfied with Bison's ratings. Knowing if someone is passive or active preflop doesn't tell me enough about exactly what he's raising or not, so I still have to double check the exact value. I've been considering implementing
this rating system, although with some minor adjustments. The weak-tight designation seems too stringent, and the Ultra-Agg definition seems too aggro. It was designed for NL, but the thought process is largely applicable to limit. What do you guys think of this?