You might want to consider replacing your SIG Model 239 with a Smith & Wesson Model 6906 (though discontinued, they are still readily available and relatively affordable). The 6906 weighs about four ounces less than your SIG, is relatively compact and has a capacity of thirteen 9mm rounds. In terms of reliability, a search will verify that most 6906 (and "Third Generation" variants in general) users report few malfunctions. After well over a thousand rounds (most with crappy agency reloads), mine (knock on wood) has yet to choke.
EDIT: Sorry, after submitting this post, I just saw where you have already ordered the M&P. I'm sure you'll like it too.
