I had 5 P Series SIG's in 357 SIG for a while there, and the P226 was (and still is) my favorite. They are great guns, as are the others. SIG has a weird idea as to what "compact" is, or was at that time, and I never figured out how the 229 was "smaller" than the 226. Its like a 226 was wearing pantyhose and sneezed and farted and stuck there.
Seriously, if you're looking at them, Id try and get my hands on each, and better yet, shoot each, before you decide. Otherwise, its likely to get very expensive.
I shot mine a good bit and never really had any issues with them. The usual rail chipping/wearing, but other than that, nothing. I had a 31 in 357SIG and it was beating itself to death, and didn't seem to be doing as well as the SIG's. Not sure why, but it was a lot more noticeable.
The only thing you're likely to notice going from Glock to SIG, is going to be the feel of the gun in your hand and the higher bore axis will likely be noticeable or seems a bit off.
I went the other way, from SIG to Glock, and picked up on that pretty quick. I had never noticed the SIG slides set up so high.
I still have a 226 and 228, and shoot them regularly, and that's just something you notice right off. I see the same thing with my Berettas and 1911's too. No biggie, or any detriment in shooting them well, just something I notice.
The other thing will be the trigger, especially if you're not a DA trigger shooter. Thats not a biggie either, but you'll probably have to work on it a little. Plus side, a snap cap, and some daily DAO dry fire at all you're favorite people on the nightly news, and you soon wont notice it at all. You wont notice the transitions either.
SIG has nice, out of the box, DA triggers and you don't have to upgrade them unless of course you have the money and feel the need. I think if you work on the dry fire, you wont have any problems and you'll save money for ammo. You remember what that is right, that stuff you used to buy to put in the mags and shoot.