The following is not meant to downplay, Constantine's well reported problems with his used Sig, and Sig's failure to do anything about what is to me an obvious factory defect.
That said, several years ago, I bought a used P290 when they were still fairly new on the market. After a short period of time, the front sight (tritium type) went dark, and I was getting light firing pin strikes resulting in 1-2 failures to fire in each 100 rounds.
A call to Sig (and yes I did tell 'em it was a used gun when I called), resulted in a FEDEX shipping label and Sig fixed both problems in less than two weeks and on their dime. This was 3-4 years ago, so maybe things have changed, or I got an unusually receptive customer service agent. Since then I've had nothing but great dealings with Sig's CS people, albeit with other guns that I purchased new.
As to your choice of a P229...my #2 son has one, and likes it a lot. Other than the typical Sig bulky grip, and the 9mm caliber, I like it a lot as well. I have size "L" hands but still find Sig's in general, have overly round, bulky grips making the reach for the trigger a bit on the long side of things...especially in DA shooting, ie. the first shot for a DA/SA gun.
Hope you like yours if and when you buy it. You might try different Sigs as some have the smaller grip diameter and a better (SRT) trigger. If you find what you want, retro fitting your 229 is an easy job. Too, if you go with a .40, and you're a handloader, brass is easy to find via the LEO or range pick up route...and it's a better SD round with more bullet weight options IMHO.
Best Regards, YMMV....Rod