The P229 is the upgrade. Prior to that the USSS used the P228. A pre-Cohen gun would be manufactured prior to about 2006. I have a P229 in .40 S&W that was made in 2002. If you are willing to buy one in .40 you can find practically NIB guns for ridiculously low money.
It still has the Sig's terrible (for me) ergonomics, but they're good quality guns.