do you mean a spray rig or the products from wagner?
A cheap "power painter" will not do as good as a good brush in the texturing of the paint.
I am real unsure the meaning of power painter.
If a spray rig, this will do a wonder ful job, but they are expensive. A spray rig requires a calm day, cutting in and go for it. It does take some experience to get the correct finish. Spray rigs use a good 20% more paint than by brush due to over spray and applications are thicker. Wind is your main culprit and could cause you to refinish your neighbor's car finish.
Now, power painter, this term usually refers to the products from waggner. The small spray righ is OK, but I would not recommend it for painting a house. The paint has to be thinned and properly mixed. The power painter roller system is also OK, I like it in some applications,BUT, you will spend more time cleaning it out than the actual paint job takes.
If in doubt, just go with a good brush, good rollers and covers, and a GOOD QUALITY of PAINT.