I have / carry a sig p229 (40s&w) on a daily basis. I love the gun, and got it for a pretty good deal ($700 shipped from buds gun shop for a dark elite model - which is well below what they generally are found for at your local fun shop). That being said, unless you get a "great" deal on a p226/p229/p220 I feel that they are a "tad" overpriced. Don't get me wrong, they are great guns - but they honestly don't do much that some of their cheaper polymer counterparts don't do as well (or better).
Some points to think of:
- The p226 is a heavy / large weapon. Remember that it is a full size service pistol... and a full metal one at that. This is great for soaking up recoil; however, it can make carry annoying. If this gun won't be carried on a daily basis, than weight is much less of an issue (more of an asset in many cases).
- Magazines are on the expensive side (not as bad as HK/Walther... but still pretty high for factory mags). The good news is that MecGar sells p226 mags under it's name at great prices (and they do / did make the factory sig mags too). I wouldn't use mags other than sig factory or mecgar.
- I was going to use this point to tell you to buy a buckmark or mark 3 22LR pistol... but honestly... for training purposes it would probably serve you better to just buy a conversion slide for the p226 so you can shoot 22lr and keep the same trigger mechanics.
- The p226 uses a DA/SA trigger system (also available in a DAO but most you'll see in the store are DA/SA). While this trigger system has some upsides, the major downside is that you will have to get used to the transition from DA to SA (if you plan to use it defensively... I suppose you could always shoot in SA at the range). It's not hard to do... but it does take a lot of dry firing and range time.
If you do want a centerfire semiautomatic pistol... other great options would include: glock (IE: glock 19... or whatever your desired flavor), walther PPQ, S&W M&P, Springfield XD/XDm, FNP, H&K P30/P30L/HK45... or you could go for a sub 1k 1911 (springer, kimber, smith, sig, colt....). There are lots of great choices... just pick your flavor (best thing to do is try to shoot as many as you can first)...