I was going to say, considering its Cali where everything is more expensive, sounds like you got a pretty good deal. If it is a true CPO, that means it was reconditioned and inspected at the factory, and it is highly likely that you got a very good condition, problem free gun.
As for the stamped vs. milled slides... they are totally different animals. The milled slides are much more beefy, and were introduced initially on the 229 I believe, for the .40 and then the .357sig cartridges. Followed by milled slide versions of the 226 and then the 239. It goes like this:
Stamped slide --> Milled slide similar platform
228 --> 229
225 --> 239
226 --> 226
For reasons unknown, the 226 was not renamed when the milled slide version was released. The frame as well as the slide was beefed up, so there are basically two very different generations of the 226 out there.
The milled slide/alloy frame versions tend to be a little top heavy. Not as bad as a Glock or HK, but there is a noticable greater weight to the slide. The stamped slide pistols balance *perfectly*, as do the ST (all stainless) guns. This is why some people prefer the stamped slides. If you know you only want to shoot 9mm, you may consider looking for a stamped slide version, as they are a little more rare these days, and don't have the rail either. All the new production 226 and 229s have the rail. I recently bought a 228 and am very happy with it.