I think you did fine, the SIG 226 is a fine weapon, I would be carrying one today if it wasn't for GLOCK Inc, unfortunatly mine is a "Safe Queen", and I will be at the range this afternoon with my G-19/26/27.
I own 2 of them, 1- W. German 1- newer I love them both. Mine are both 9mm but that's just preferance. Have you looked into changeing the grips yet? I Don't mind the plastic p226 stippled grips mine came with but my girlfriend hates them and swears by her hogues. just a thought.
For the 9mm you can get 18rnd. non extendo's for the same or less as factory's but I don't know what they have for the .40