A friend of my nephew bought the game awhile back, and plays on the house LAN. He has an uncanny, (positively scarey), "feel" for the center of the screen. This is the only person I've seen that consistently buys a second 9mm. As a Sharpster, he prefers dual 9s, dual HCs and the LAR. At times, I've left my seat during games and gone and stood behind him as he played. I've watched him consistently decap Sirens while they're hardly more than a dot on the screen with the double 9s without even raising the pistols to eye level. And I think, "How the hell does he do that?" It's a little creepy.
On certain maps, he'll practically single-handedly run the table with just the dual handguns on the first four waves, leaving everyone else with little to do. It isn't a case of art imitating life, as I've taken him to the range a few times, and quickly learned he can barely hit the ground with his hat when it comes to real firearms. Sadly, once the KF heavyweights start showing up, he gets rattled and isn't exactly the textbook example of the ideal Sharpshooter. We're working on that...
On the subject of aiming two handguns; we women have the reputation as being (possibly) spatially dysfunctional. While I don't feel impaired myself, I've a few female friends that seem a bit challenged in this regard. "Rhenna, do you think I can park my car in that space?" "Joanne", I answer, "I think you could park a freakin' school bus in that spot." That point now being established, the only advice I can offer regarding aiming dual pistols would be for elevation.
I find that for the 9mms, use the bottom edge of the white dot on the front sight as your point of impact, elevation-wise. For the HCs, use the top edge of the front-sight white dots. (This is, of course, with the pistols raised to eye-level.) By this I mean, imagine a line drawn horizontally between these two points on each pistol. That is, at least with my eyes, where the round will go height-wise. You still need to estimate your windage, (left-right), and discipline yourself to re-aim between shots, most especially with the HCs. Yes, as a reference, all this may seem a bit too fussy. It does work for me.