[ano]

My experience says that there are common rules for abilities stacking and not stacking.
When you cast more than one spell with similar effect (giving regen, prec, mr, quickness or anything else), only the highest of all effects will work.
OTOH, when you use multiple items with similar effect, the effects stack and they will also stack with the spell you cast.
However, it always seemed to me that you can't cast personal regeneration when you already have regen.