The Pmags are impressive tech. Yes, they are high impact plastic, but that gives advantages metal mags cannot. The Pmags bend and deform when a lot of pressure is placed on them. They then bounce back. Metal mags won't do that, and if they are damaged or pressed on, they will be bent and they either have to be dismantled and reshaped, or thrown away.
That said, I've been leaning back towards metal mags myself. Just out of simplicity's sake. I don't plan to get rid of my current Pmag stock, though. And if I can no longer find teflon coated mags for a decent price, I'll always have Pari- Magpul.