REALLY ??!!?? Almost 10,000 rounds, you say ??? How long have you owned that thing, anyway ???
Let's see ... at MidwayUSA online prices (low to average in the industry) ... let's call it @ $15 (average of all brands) for a box of 20 .357 SiG JHP ......
Sooooooooo ... "almost" 10,000 rounds/20= @ 500 boxes .... X @ $15/box = @ $7500.00 for ammo ???!!! 
Now that's a LOT of shooting ... "almost 10,000 rounds" .... and "almost" unbelievable. 
Um, lets see, I've owned this pistol for about five years now.
Oh yeah, I did forget to mention that I was on the Navy shooting team for four years, hence government ammunition, unlimited range time, plus reloading equipment at hand to make my own.
If you'd like, I can post up a picture of my shooting book that I've recorded all of my shots in. If that's not enough, come look at my gun sometime, then you'll see the wear of the blue, etc, to see that the gun has been shot that many times.
Oh yeah, I've also probably spent 3-4k, if not more, on ammo and ammo components, just because I like shooting that much. That's not including the rest of the rifles and pistols I currently own, which I've shot almost as much.
If you want, I can send a copy of my NRA national pistol record that I currently hold, just to verify that I'm an actual shooter, if you'd like.
Please. This is crap and most of the gun types here know it. Don't infect others with this myth. SHOT PLACEMENT SHOT PLACEMENT SHOT PLACEMENT. That's what it comes down to. A 9mm JHP in the vitals is just as effective as a .45 JHP. Believe it.
Exactly, shot placement is the best friggin way to make anyone go down. Practically any bullet in the vitals, except for maybe a .22, will make someone go down fast. However, in the heat of shooting most people can't hit it. A 9mm doesn't have the energy for an off shot to stop someone completely.
Here's an example. Before I joined the Navy I worked with my local police department. While I didn't actually witness the shooting, one guy had to put 5 rounds of 9mm into a dude wacked out on meth. His partner, carrying a .45, put one in the next guy's chest, went down with one shot. Again, I didn't see the shooting but I read the report.
The biggest factor in the lethality of a cartridge is muzzle energy and the ability to leave an exit wound, specifically the size of that hole. A 9mm can exit, but because of it's smaller muzzle energy, the exit wound is a lot smaller, if it even exits. A .45 will blow a hole about the size of a barn door out the back, which pretty much screws anyone who gets hit by it.
I carry the .357 Sig round. It actually uses the same bullet size as a 9mm, but because of the pressures and powder grains used in the cartridge, the muzzle energy comes pretty dang close if not equal to a .45 (a.ka. bigger exit hole). Another reason I carry the .357 Sig is because I own a 9mm that I like to plink with so I don't have to buy two seperate bullet types when reloading.
In addition, being on the Navy shooting team, I've met countless shooters, actual guys who have experienced actual combat shooting, who sing the praises of a .45 versus a 9mm.
Say what you will, 9mm doesn't pack what's needed. Never will, unless you're an ace shot that puts a round between the eyes or through the heart every time. Why else is the military trying to go back to the .45 now? If the 9mm was good enough, why change?
This is bad gouge. BAD gouge. Derringers are notoriously difficult to aim and handle. Most gun fights are over in about 4-5 shots on average. One or two isn't going to cut it, especially if you can barely hit your target. A dedicated CCW pistol such as a mid-size/compact Glock/SIG/HK or a revolver are leaps and bounds a better choice than a derringer type pistol.
Using your response above, SHOT PLACEMENT, SHOT PLACEMENT, SHOT PLACEMENT!!!!!! If you have proper shot placement and trigger control, one shot into the vitals will take anyone down, something you agreed to yourself. Most gun fights are about 2-5 shots, and a distance of 2-5 yards.
My point about the derringer was that if you want the ultimate of concealability then get one. It's small enough to stick in your shoe, if needed.
I myself said I carry an H&K in .357 Sig. Why? Because I know from my experience that pressure situations tend to make less than ideal shots, so I'd prefer to carry something with more rounds and more punch. If you're good enough, a derringer will work just fine.
Finally, what's with the friggin hostility here? I'm trying to post good advice that I've garnered over the past 15 years of my shooting career. If you guys who shoot recreationally have issues with it then so be it, but my opinions come from countless years spent on a range putting lead on target.