Rab,
Got one myself, great for the range but if you have a well regulated trigger there's really no need. I would say NEVER use it on live targets, the variables are too great of a shot going off when you are not 100% ready for it... in the heat of the moment with the 'fever' running through your veins. You can adjust a Sako trigger to a nice crisp let off without using anything so light and potentially unintentional, they are very light when "set" !