I'll give you an honest 100% assessment of my satisfaction when I received my Kozyheat and how I feel now; I'm a no BS kinda guy, and I am very critical of small details.
First thing I noticed was that the 2nd layer heat shield above the firebox was bent down. This shield is only supported at it's attachment point on the sides. It is very thin sheet metal and very flimsy. That's not a problem if things are done right, but IMHO, they weren't. Kozyheat puts a very slight bend/crease right at the front edge of this sheet for "strength". But the bend is so small and so close to the edge that it doesn't help at all. The "lip" simply buckled and now that shield sags down; mind you that it's been like that since I got it, I didn't cause that in any way. It still bugs me after burning with it since October. Even with the front, top grate on, you can see this crooked/bent/buckled sheet metal between the bars. This is a fail on their part IMHO, any competent sheet-metal fabricator and/or engineer should have been able to see this design flaw long before anything was produced.
2nd gripe, this one is another very poor design but you only deal with it during install and only if installing ducts. There are 2 duct punch-outs on top. I think they area laser cut in there so it's a very thin cut line. The problem is that the punch-out is held in place with 3 connecting tabs vs. the 2 tabs that most have. With 2 tabs you can just twist it back and forth until the tabs fatigue and break/tear. With 3 tabs you have to somehow cut one out before you do this. So now you have to pry/twist it up to get cutters in there. This is a bit challenging, but the real trouble comes next. Under that outer shield is the same punch-out style that also needs taken out. Now, with mangled sharp edges along this hole you're reaching through twist/pry and cut the 2nd punch-out w/o cutting yourself on the sharp edges. Oh, I forgot to mention, this is in the 2nd layer heat shield mentioned above so if your heat shield wasn't damaged previously like mine, it's going to be damaged by the time you get those punch-outs out of there.
3rd gripe was that it seemed to burn very hot very fast no matter what I fed it. I've since then determined that I simply just have too much draft. I have an ideal draft condition where I am but I still wanted me chimney to meet/exceed code. My chimney height was really close to meeting that with a 1 foot section of pipe in it. I wanted to make sure that there was absolutely no question as to whether it was high enough or not so I decided to change to an 18" piece. They didn't have one at the time so they just gave me a 2 foot piece. I think the extra chimney height coupled with ideal draft conditions gives me "too much draft" if there is such a thing. Sometimes if the conditions are right the secondaries are clearly putting out wisps of air/flame that are 10+ inches long before they "blend together". You can tell that the draft is sucking air through the secondaries pretty hard and I may be losing a lot of heat out the top because of that.
4th gripe, they used some sort of silicone or high-temp silicone to stick the door gasket in place.Well, when silicone is overheated it turns to a white, crystalline powder that won't do jack. my gaskets all came off when I opened the door after my first fire. So I had to try to hold them in place and close the door so it sealed enough until that fire could die down all the way. Then scrape all the nasty powdered silicone residue off, try to get that off the gasket and then redo the gaskets. This was plain stupid and un-called for. Simply no explanation for it except lazy, cheap, or just too stupid to know the difference. They do send a tube of stove/gasket cement with the fireplace though so it didn't cost anything for the repair other than time and frustration.
5th gripe, We have the Z42CD model. The one handle is welded fast to the door and the other has is adjustable. The adjustable handle has a flat spot for the set screw so the latch stays put. This is all fine, but the 2 handles are attached at different angles. One of them sticks almost straight down and the other almost straight sideways when latched. So it looks horrible, almost like you've left the door unlatched when it is actually fully latched. There is no way to adjust the handle angle on the adjustable handle and still maintain proper functionality of the latch. This bothers me a lot too.
What do I think now? I love it. For my uses, where I've ducted the heat it is working great, my family room (location of the fireplace) doesn't get much warmer than the rooms where we ducted the heat. I can load up at night, get a good 7+ hours of sleep and still wake to a fairly warm fireplace and a good bed of coals to re-light from. I'm not saying it will keep the house up to temp overnight without a reload but that doesn't bother me. I get up for work almost 2 hours before my wife and I load it and she is happy when she gets up. The door opening is huge, really nice to put wood in, but that is also a small detriment that I'll touch on shortly. The air control is fairly easy to operate; I've found that the only time I have it opened is on start up. Once I get flames going enough to start heating the secondary air tubes and refractory panel up I can close the air completely off and the secondaries will take off and go like crazy. I think that is due to my excessive draft but I've gotten used to it.
Oops, ran out of characters, I'll continue below. Sorry for being so long-winded.