Firstly a side note for JohnKSa about vascular damage: I have seen cases (not many, granted) where intimal flaps were found in the arteries of gunshot victims by means of angiography. In these cases the vessels were patent but partially occluded. These were differentiated from extrinsic compression (by haematoma) by the shape of the filling defect. That differentiation was done by the South African radiologists involved in the case. Certainly though, your money would be reasonably safe if you bet on a handgun round not being able to cause tactically significant incapacitation by means of damaging vessels by the effects of the temporary cavity. Nevertheless the presence of the intimal flaps needs to be considered if the question is asked regarding temporary cavity as a possible cause of these filling defects in vessels.
I'll tell you gents straight away what my background is, so you can dismiss or take stock of what I have to say from the outset. My primary qualification is diagnostic radiographer. My training and experience is from SA, and the hospital where I worked in JHB would see about 150 gunshot victims every month. I worked more than 3 years permanent night shift there and I saw many gunshot victims, somewhere around 3,000 probably more (if I include my day-shift years and training too). But the really interesting thing I was able to do was conduct formal research into live gunshot victims in 2002 and for that study, I had a sample of 150 victims from a pool of 542, in a four month period. Here is what I set out to do for my research cases:
1) Record all the clinical findings upon admission, including the location of skin breaches.
2) Photograph all the wounds.
3) Examine any clothing accompanying the patient and photograph any relevant breaches in the fabric.
4) X-ray the victims, or supervise the X-raying of the victims, with careful instructions to mark the surface breaches with radio-opaque markers for radiologocal trajectory plotting.
5) Document the treatment of the patient.
6) Accompany the patient to theatre, in certain circumstances.
7) Review the notes for surgical findings.
8) Photograph any recovered projectiles.
9) Develop an overall understanding of the teminal trajectory of the projectile.
This is quite a big project and I am still not finished with it, but I'll give my impression as it relates to this discussion. As many have pointed out, there can be miraculous escapes for many of the victims. I would say that typically in my research an escape was due to one of the following:
1) A terminal trajectory that penetrated to a reasonable depth but missed all the vital structures.
2) A terminal trajectory that was subject to deflection, away from a vital structure. Deflecting structures in my cases were items of clothing (such as belts), bony structures such as the skull, or in some cases soft tissue deflections (the projectile suffered a course change without any hard surface deflection).
3) Fragmentation of the projectile such that the trajectories of the daughter fragments were deviated from vital structures and/or the decreased energy of these daughter fragments resulted in decreased penetration of the victim.
At no point was I able to make a comment on the effectiveness or wounding potential of any one calibre relative to another. Most of our cases were due to handgus of service calibre, but there are several variables present in real shootings that are not duplicated in the laboratory:
1) Distance to target.
2) Angle of incidence.
3) Different clothing materials. The most unpredictable of these is the shoe. I had big problems with gunshot wounds to the foot where shoes had been worn.
4) Variables related to the weapon that could not be quantified due to lack of evidence.
5) Number and placement of shots, while simultaneously applying the variables above.
I don't think it is worth getting into a calibre war. There are too many variables in real-life shootings to arrive at a scientific conclusion about service calibres with any kind of certainty in my humble technical opinion. A lucky deflection for one guy may result in death for another. You really need to go through actual cases to get some understanding of the difficulties involved here.
There are probably a few things I have left out and I do have a huge amount of material related to gunshot wounds, but that is my opinion about calibre as it relates to this discussion. One of the things I would liked to have done is get access to data for dead-on-scene victims during the same time period. Unfortunately I could not do this. However several of my research patients died after the acute phase and I have general data on the whole pool of 542 gunshot victims, including the position of the wounds and the outcome/designated treatment area of the patients.
). I happen to prefer my .45auto but dont climb up somebodys 
anytime I hear them say they like a 9mm over a .45. Some people (women) find the 9mm a more comfortable round to handle, less recoil, etc. Any round is better than no round, and a 9mm or anything smaller in your pocket is better than a .45 in the truck. To each their own.
and the BG is on top of me, I can empty the thing 's nine rounds so fast it sounds like it's gone full-auto, and reliably. I'm not sure why, but the Jetfire is far more reliable than the newer and larger caliber Tomcat. 
