Having watched your review it made me think of a few things.
Although the rifle is heavier the barrel to me looks absolutely great, the points about the tapered barrel made me think about something, so far as I know rifling wears out the most or quickest in the first few inches of the barrel. I wonder if this tapering system will reduce this?
The quality of engineering sounds good, I personally if I were to buy the rifle would prefer it to be entirely made in Germany after all they make the best steel in the world and have excellent quality standards as you showed.
The weight may be an issue, personally I thing the hand guard does not need all that weight and perhaps would be best made out of aluminium, I am no expert but I trust HK on this one and prefer quality to weight loss. You only need one good quality rifle, and why settle for anything other than the best?
The allen key for stripping down the rifle seems to me to be the result of HK thinking they can get away with it as its for civilians and sporting reasons. This irritates me, however I would imagine a fellah might be able to adapt some normal allen keys to fit.