'pilotmike' and 'katamarino' - I entirely agree with your comments with respect to the Commercial Pilot Licence and the testing, training and extra discipline required. I am an experienced private pilot; my partner, also originally a private pilot, became a CPL holder several years ago, The style and professionalism of her flying impresses me, and gives me confidence in her capability and judgement. I still have more flying hours than she has, in a wider variety of aircraft and circumstances, but I'd rate her flying judgement over mine any day. The careful professional way she prepares for sorties - her commercial work is not airline flying - is a pleasure to watch.
I wondered beforehand whether a CPL would really make any difference - it most certainly does. It is in my view a significant step up and beyond the PPL level, professional though I try to be in my approach.