Non-standard height, big deal. The continuous upper receiver rail and RAS are a tiny bit higher than an AR upper. I actually perfer it over the height of AR's.
Get annoyed all you want over the movement of the pins, it was necessary to comply with German Federal Law, otherwise you would not even be able to buy the guns as a sport shooter. Good on HK for even bothering to make civillian legal guns, they could have said that it wasn't worth the trouble.
I'm not sure what neutered version means. A bit confused as the standard Hk 416 and Marine's IAR are exactly the same, without the full auto settings in the lower.
Here's another fact for you: the MR223/ MR556 have their 16" match barrels pressed into the upper receivers after the receivers are heated. A bit different process than the standard Military rack grade HK 416, done for increased accuracy of the civillian gun. The barrel nut is just a secondary means of securing the barrel to the upper reciever.
Here's another one. The longer mag well that isn't compatable with some mags like standard magpuls was done on purpose. The German engineers didn't like the way the standard AR mags were attached and felt it allowed for too much play with the mag in the mag well. They wanted to have the mag secured a bit better. Then they went and built their new HK steel mag. One of the best mags ever produced for the AR, only to find that it's heavy and when you throw them onto cement and stomp on them during training the feed lips bend.
I doubt that all of the other psiton AR's are "just as good". They are not and it has been proven in testing. If it's important that you save a $1000, then you've made the right choice, but you don't have a better gun.
Rich