This forum has been a great source of information and one of the primary reasons I bought a Z2 and then when it was stolen I bought a Z3. Finally after suffering through the high levels of noise in high ISO ranges I crossed over to the dark side and bought a Canon Digital Rebel XT a few weeks ago.
What I learned after living with the DRebel is it just blows the Z3 away in many areas. Of course you can see this isobvious by looking at the spec sheet. What the spec sheet doesn't show you is howsome of the numbers actually translate into real performance differences. At first I thought that I'd sell my Z3 after using the XT for a while. What I learned is that the Z3 is still a pretty nice camera.
Sure it's low light focusing performance isn't great, it has a fair amount of noise at higher ISO settings and a few other quirks but all in all it is a pretty good camera even when compared against the XT. I do love the movie mode on my Z3. It boots and focuses pretty quickly but is in a different universe compared to the XT. But I love that I can easily stick it in my jacket pocket. I can only do that on my XT with my 18-125 lens (which is like 35-200mm equiv). I love the IS of the Z3 whereas just one lens I bought with IS for the XT cost almost 3 times the entire price of theZ3 so it isn't fair to compare in some ways. OTOH, what price can you put on getting a once in a lifetime shot or not?
The Z3 is an amazing value for the money. I'll still use it for the movie mode and in situations where I don't want to risk my XT and lenses. I have very few regrets buying the Z3 and if KM fixes the low light focusing issue with maybe an assist light and give afaster lens which could help offset the noise issues, I'd definitely buy another. Its noise performance is no worse than others in its class but this entire genre' of cameras with small sensors have this issue.I became tired of noise spoiling some really nice photos. Even with Noise Ninja and Neat Image I could only do so much to reduce the noise. I can shoot at ISO 1600 on my XT and have less noise than my Z3 did at ISO 200.
If you are looking for a very good performing dSLR and don't want to spend a fortune I suggest you consider the new Canon Digital Rebel XT/350D. Definitely a lot of bang for the buck. I considered the KM dSLR but it just wasn't the value the Canon was but the thought of internal IS was definitely tempting. Ultimately it came to do a better and bigger user base and a lot more lens choices for me.