I have the Stihl KM55 the smaller engined combi system with the interchangeable heads - chainsaw, hedgetrimmer, brushcutter.
I use the saw head mostly, it is very good, there is even a extension to make the pole longer.
This has been a great buy, I have used it on storm damage trees, when you dont want to get to near hanging limbs etc.
It is also good for clearing the lower branches preparing for a removal.
Pruning with it is not a good idea as accuracy is difficult to achieve due to angles and lack of better control that you would get if you were right up close to the target prune sight.
Wear eye protection the sawshavings fire right at you!
I will go for the bigger engined combi system when I have to replace the KM55, I think it is called KM130R, not sure though.