Edit: I should have mentioned in the OP that I have the railed (which I hate) variety of the 3913TSW. It has been changed. I just bought a "normal" 3913.
Okay, I had a chance to tote around the new hardware today and here are my opinions.
-It carries extremely well. It is my opinion of a perfect carry 9mm, if all-metal and hammers are your thing. The size and weight are exactly right to hold comfortably, carry all day and shoot accurately, without getting beat up.
-I hate the factory grips. However, for a carry gun they are useful- here's why: I practiced my draw from a concealable (tight to the body) OWB. With the Hogue rubbers (which I like), I found it difficult to get a firm purchase fast. They take up too much space between the gun and my body. I can only imagine this being worse IWB. (I don't carry IWB, so I don't care.) A lousy grip and/or a clumsy draw can be the difference between life and death. The smoother, thinner factories allow me to get my thumb all the way around the frame and if my grip is a little off, I can "slip-n-slide" to correct it before I get on target. The Hogues are too "sticky" to do this. (FWIW the 3913 w/ Hogues is approximately the same size and width as a Glock 19.)
-The spurred hammer is useless on a carry pistol. I'm not gonna cock single action before I shoot a BG. Second, on a DA/SA, I carry with the safety off. I would hate for the spur to get snagged and cock itself SA. Thankfully, I only use holsters w/ a covered trigger. I'm probably going to trade hammers with my [spurless] 3913TSW, as this is the carry gun and the TSW is [now] the range gun.
-The sights suck, but I don't care. If this is like the other 3rg gens I have (i.e. the TSW (same sights)), I will shoot the fixed sights low. However, I point-shoot my SD pistols, so it doesn't matter. If I need a longer shot, I'll compensate or buy a taller rear. (After starting with revolvers, I've grown to hate 3-dots.)
-Pinky rest mag floorplate > flat. The pinky rest mags fit my hand perfectly. The flat base ones are kinda awkward for me.
All in all, IMO it is what a hammer-fired carry gun should be. The only detractor is the hammer, which I can fix.
I can't wait to get it heated up at the range!
On to the next topic, 3913 vs Shield 9? (getting the popcorn)