I use an electricians knife to score the cable the split it with my fingers and then open. Gives a nice neat end to the sheath instead of that rough end you get with pulling the earth out. As well I have been told it can stretch the earth and increase the PFC quite dramtically. Bit purist I know but its nice to be a craftsman and do the job nice and neat.
I've heard that about stretching the earth as well, but has anyone ever tried to stretch the CPC? I think you've have to work really hard to stretch it enough.
I know what you mean about the raggedy edges and I have to say I prefer nice clean edges, but I'm kind of wary of using a knife for fear of damaging the basic insulation.