I really like my 229RDAK. Not sure how familiar you are with Sigs but I can give you a few tidbits:
Great safety system that includes four basic safey features:
Decocker (pretty obvious), drops the hammer safely on a chambered round
Intercept notch - catches the hammer as it falls using the decocker. Holds the hammer away from the firing pin and acts as a drop-safe mechanism
Disconnector - lifts the trigger bar as the slide moves rearward to prevent firing out of battery
Firing pin block - prevents pin from moving forward unless trigger is pulled to rear.
ETA - Oh ya, forgot to mention the obligatory "remember, all mechanical parts can fail"
If this is your first Sig, I would highly recommend the Sig Armorer's manual done by Chris Orndorff. It's less than $25 and is a great resource for maintenance procedures and understanding the Sig Handguns. Top Gun Supply is also a great resource for resource. I'm not affiliated with either, just passing along my experience. You can find Topgun Supply here
I can't help much with the age, I can only tell that on the older West German models. Gotta go now, maybe someone else will chime in with more info.