This I do agree with, but it doesn't just apply to SIG. The market is flooded with firearms and you can get excellent pistols, for 2/3 the price of new in the case of SIG. I still look out for the earlier Glocks with the frying pan finish that to me holds up better, I find the older pistols eject more consistently (even after the changes made in the last few years), and they're less money than new.
I saw a Tyson's Corner P226 at an LGS the other day. Mud rails, 1987 markings. To someone not in the know it looks maybe a year old and the trigger on this one was like butter. If I didn't have to put money away for the house I would have picked it up in heart beat. It was $625. That's hundreds less than new.
SIG's current pricing structure frankly confuses me. The Legion series to me was a necessity because they had to find a way to keep getting people to spend close to $1000 for new pistols and by marketing it as a premium product for the elite they can target a demographic with more money. The LGSes around me have shelves of used ones because even at used prices they are a hard sell for many people. They have to drop the prices down to $600 or so to get them to move, but that means they can't give people much at all when they go to trade them in. Then you get some pissed off people wondering how the $900 pistol they bought is now only worth $600.
To me the P320 series is probably the best bet for modern day SIG. There doesn't need to be as much attention to detail in production and they're cheap enough to produce to sell at prices the market seems to accept. I've owned two and while I don't think they offer really that much more to the market (the conversion kits aren't my thing) I do think they're generally reliable and people seem to like them.
I have had decent luck with some of the recent production pistols, though I admit the finish and fit isn't as nice as the old ones. And they've been reliable for me. SIG rifles I frankly wouldn't touch. I see people have issues with new ones at the range consistently (even after multiple trips back to SIG) and I've seen loaners from the SIG Academy have issues as well. I've seen loaner pistols from the Academy have issues too, in full disclosure. What's funny is the force on force pistols are the old German models with the UTM conversions and they work great.
I guess I agree with you more than I disagree with you. SIG's focus now is production numbers and it shows. I do still think you can get a decent pistols, but you should be on the lookout for issues. Though frankly in 70 some pistols over the past 5 years, similar to you, I've seen plenty of new pistols with issues. I think that's just the state of the industry now. And you're right; if people pay attention there are so many great deals on used firearms.