So far I've bought two P6s. The German guns have worn finishes etc. but mechanically they are very sound. I've probably taken apart/inspected 20 or so of them. All of them in good condition with no excesive wear. If you have a few $$$ laying around you can send it to SIG and for $200 they will make it factory new for you (refinish, new springs, new sights etc). The triggers on them are REALLY heavy but aftermarket springs will take care of that quickly and cheap.
The two I bought I cleaned up and refinished the slides. Both have been great shooters (like al SIGs) and 100% reliable. I resold both to friends that needed good basic SD handguns for what I paid for them and they are in love with them.
Last I checked Brownells was selling new factory grips for them for about $14 a set but that was months ago. They might be out by now.
I like the single stack because they make the SIG a nice compact carry gun. Here is a side by side comparison with one of my Kahrs (K9)