"Very good, congrats. How do you think it stands up against the M&P15-22 for accuracy & reliability? Do you think this is a valuable addition to the AR style .22 market or just a good novelty?"
IMO.....
I own both the HK(Umarex) and the S&W 15/22. Actually 2 of each brand. I can honestly say that the HK(Umarex) is one of the most accurate semi .22's I have fired. That being said, the S&W is also a tack driver! The HK feels like a real AR rifle and the S&W feels like a toy. I have shot approx. 12-15k through the carbine, only a couple hundred through the pistol version. I am consistantly shooting blackbirds in my back yard at 80+ yards with a simple red dot. The only complaint I hear on the HK is ftf or fte. If the people would read there manuals they would realize you need to adjust an allen screw for the ammo type you are shooting. I shoot CCI standard velocity with a Silencerco Sparrow and have NEVER had one problem. The ONE complaint I do have is it is a B**CH to clean! If you dissassemble all the way down you have to re-zero your optics. For some the diss. Will take a PHD to complete!