I'll second the motion to use some grease, rather than oil, on the frame rails. I also use it on the unlocking lugs, since that steel barrel slams into them with a lot of force.
I have a 6906, and it's my concealed carry pistol about 99% of the time. I like the safety of the first shot being double action.
It seems like EVERY time I read about somebody shooting themselves, or having a negligent discharge, it's always a Glock.
Very rarely, it's another striker fired pistol with no manual safety. In my mind, carrying one of those makes about as much sense as carrying a revolver with the hammer cocked. Yes, it won't fire unless you pull the trigger, but damn: that's a stupid way to carry a firearm.
Your 6904 is an excellent semiautomatic pistol. Smaller than the full sized, or 'service' size pistols, yet not so small that you can only get 2 fingers on the grip. It's a perfect size for concealed carry.
They are quite accurate pistols, with the very nice and highly visible Novak 3 dot sights.
The 6904 will handle +P 9mm ammunition, but I would recommend that you do most of your shooting using standard pressure 9mm ammunition, to save on wear and tear on the frame. After all: S&W isn't making them anymore.