I love 1911's and I understand new shooter worries but that is why I do not advise any shooter to purchase and carry a 1911 as their first gun. I think it was Masaad Ayoob (but I will stand by for correction) that said if you treat your carry gun like a lawn mower get a Glock or a Sig, if you treat your carry gun like its the pride and joy of your muscle car collection than get a 1911.
However getting back on topic...
I cannot speak to much of the Sig line as I have had little experience with them. However my family has some history with the Pietro Beretta Corp and I can assure you the decocker on the 92 series pistols are full proof.
Get out your 92 if you have one or if you have a good imagination follow me a little bit. Unload your pistol and keep it pointed in a safe direction and cock the hammer all the way back. At this point look at where the hammer falls into the slide. you should see the back side of the firing pin staring at you. Slowly press the safety/decocker down and you will see that the firing pin is not a firing pin per say. It is a piece of the firing pin but it is completely disconnected. It sits in a rolling mechinism that rolls up when you press the safety/decocker. So when the hammer falls in only contacts that round bar. It never comes close to the actual firing pin. There is no way that the hammer can contact the firing pin during a decocking action because the pin in a sense moves out of the way.
Hope that clears some things up for my Beretta friends.