Personally, I think these are two separate guns for different modes of carry. It's like comparing Grapefruit and Oranges. Both are citrus, but both are used for different reasons.

The 3913 / 3953 is a prime example of a great carry / shooting gun. However, I limit my carry of these two firearms to either OWB or IWB carry simply because they are on the heavy and bulky side for Pocket Carry. These guns are also MUCH MUCH nicer to shoot. My 3913 had 1200 rounds through it in a point shooting class over a weekend with no failures, jams, or anything like that. I also only had 3 magazines (THAT part SUCKED, I took care of that when I returned, I now have 8). It's a pleasant accurate gun to shoot. My 3913 is currently retired and I carry a 3953 as I wanted something easier to conceal and this gun with it's flat edges and DAO trigger fits the bill nicely.

The LC-9 / PF-9 though was designed to be carried in a pocket or IWB. It's small enough to fit this role, without being overly large. The LC-9 isn't bad to shoot, but I wouldn't want to spend all day, or even an hour at a range with it. 4 mags through it and I'm probably done. However, it's not meant to be a range gun, but something pulled as a last ditch effort from a pocket.