To re-state my position...
The only "left handed" option I absolutely must have is a safety/decocker on the right side of the pistol. Even when the gun has the option of ambi mag release, I still use my middle finger. It's the only thing I can think of that's actually FASTER than the way it was intended. I use my index finger for releasing the slide.
Now having said that, there are certain pistols (like HK) who's controls on the left side (right handed) are more adaptable to using the middle and trigger fingers. The farther forward the mag release, the better HK, Walther P99, etc... all have that, but I have found that most any semi-auto is perfectly fine, EXCEPT the Glock. It's the least usable (to me) straight out of the box with the middle finger. Yes, you can file the corners, and install a mag release extension, but out of the box, it doesn't do well for me. The same goes for the slide release as well. The farther forward it extends, the easier it is get hit with the trigger finger. Glock could be made MUCH easier to use, if someone would make an extended slide release that went THE OTHER WAY!!! All the ones I've seen extend further BACK, with a neat little bump at the REAR. I need it to extend FORWARD with a bump on the FRONT.
But anyway, I do agree that Lefties just have to practice using right handed controls for the most part. But saying "it only takes an extra second" is not acceptable to me. It must be just as fast, or it's a hazard!
One more thing... I disagree that revolvers are "leftie friendly". I have one, and it didn't take long to realize that "speed reloading" was much more difficult since the cylinder swings away from my body, and I either have to change hands, or cross my right over my left to use a speedloader. Not a pretty sight.