I live in Pittsburgh, where the weather can be harse, and the water even more harsh. I installed CPVC throughout the entire house & garage back in 1989, and have had NO problems whatsoever. Not one single leak... not one single pressure problem... nothing. I used a quality line of parts & pipe (Genova), and did the job correctly.
The key word here being "correctly". Needless to say, I haven't done a sweat joint since then, and have no desire to.
Gluing plastic combines the two pieces on a chemical level, and thus, the piece becomes one.
Sweating copper is nothing more than filling a gap with tin. Do you really have to be Einstein to see the difference there?
Those who say that copper is better than plastic are not only living in the stone age, but it's unlikely that they've truly done their homework in this matter.
Shoddy manufacturing (the polybutylene issue a few years back) and shoddy workmanship aside, those who say that copper is better than plastic might even tell you that vinyl records are better than CDs. Some people just don't deal well with change and/or progress.
And as for most plumbers being so against it, that one's a no-brainer... they can't make money on installing it, and when people do it themselves and realize all of the benefits, the plumber and his 1950's copper mentality (as well as his ever-present propane torch) becomes something outdated, and certainly not needed.
The more they argue against plastic, the more foolish they sound.
Granted, there are still situations where copper is the way to go, such as with boilers and so on. But to completely rule out plastic is inaccurate and self-serving. In this area, the water companies and the building inspectors have no problems with plastic; only the plumbers are the ones crying in their beer.
Do your own homework and see what conclusions you come up with. As for me, my house has been leak free for almost 14 years, and it didn't cost me a fortune, or sweating headaches, to make it that way.