I just joined this board based upon the purchase of an UZI carbine. I selected this carbine for a niche use and find that it will fit the bill quite nicely.
Allow me to explain the niche that this weapon fills for me a little better so that my perspective at least makes some sense.
I have spent the last 24 years in law enforcement where I spent 19 of those years assigned to my agency's SWAT unit. When I first came on the team we were issued MP5a3's which I carried for about ten years prior to switching to the Mk18 (10.5" M4). In these ten years I racked up hundreds of situations where the MP5 was deployed in an operational situation. These ranged from barricaded gunmen and high risk warrant service to hostage rescues. In each the MP5 served well and in each was well within its operational envelope. To say that the 9mm round is not effective is simply folly as at ranges which are common in LE engagements, i.e. urban, the MP5 and the 9mm can more than get the job done as long as you do your part with bullet placement.
Just to touch briefly on why our team switched to the M4 platform: cost. Over riding everything else cost was the determining factor. MP5's and the accessories for them are many times the cost of same for an M4. Sure the M4 does give us the ability to range out further but honestly in an urban environment, at least our heavily urban environment, we were always within the range of the MP5. Next, the 5.56mm does penetrate body armor however to be honest that concern is vastly overrated. Very, very few people have body armor. Yes there have been some instances, all high profile instances where body armor played a part in the engagement however they are a very small percentage.
I have been present during several officer involved shootings and can bluntly tell you that the suspect who got shot didn't know what they got shot with, period. From 12 gauge slugs, to 9mm, to other weapons systems as long as the bullet was placed correctly then everything went well.
Now the niche that this weapon performs for me: I now teach tactical law enforcement and officer survival nationwide. In that regard I travel a lot. While I traditionally travel with a 16" M4 style rifle, for some classes the M4 is simply not needed but I do want some type of long gun along just in case the literal 'worst case' scenario might erupt while I am far from my family.
What the UZI gives me is the ability to have a reliable weapons system with me in a very concealable package. I can either break the carbine down and without the barrel have it fit inside a messenger style look alike bag or I can choose, where lawful, to take the UZI SBR along with suppressor.
No, it doesn't give me an extremely long range platform to work from should I have to however I would put it like this; many people theorize about 200+ yard engagements. Could happen, has happened, but the more likely event is 0-50 yards and in that scenario I will take a weapons system that is quick to shoulder, has 'enough' stopping power and one that lets me have contact with the weapon at three points, i.e. shoulder, cheek weld and hands.
Yes, there are those who can shoot a handgun at longer ranges and expect good solid hits on a target, in fact I have personally seen a very well known trainer do it at 400 yards with a 1911. However, that was on a square range without any movement of the target or shooter and it was not under duress. For those who think that 100+yard handgun hits are likely in a real, moving combat scenario I think you are deluding yourself. Sure it can be done in the abstract but being able to do it on demand, in a real world engagement where your life is on the line is not likely.
Can you hit a target at 100 with the UZI Carbine, yes, but again it was not a system designed for that. It is however, a better solution than a pistol at that range.
Where the UZI is better than the 5.56mm/7.62x39mm is in size. You can conceal it better and it can be deployed from concealment easier, especially in the SBR versions.
If I'm going to all out combat, the M4 platform is my first choice followed by the AK platform. If I am forced out, literally on foot during a SHTF event while I am away from home and outside of my normal jurisdiction, I want something that I can conceal yet something that gives me the three point hold that the UZI carbine does.
Is the UZI or UZI carbine better than the MP5 or MP5 clone? On price alone yes and on size.
Again, while your mileage may vary, for me the UZI Carbine/UZI SBR fills a niche. Narrow as it is, it is still something I felt needed to be addressed for my safety and survival.