This is just my experience with this board. When I got it, it was almost mint the guy had rode it for 2 days on beginner slopes, got hurt and decided to give up on boarding. a few superficial scratches on top sheet and base.
As for the core, Yes it does not extend through the nose and tail. How do I know this? Because I can see it. The core runs about a cm longer than the rails.
The base of my board is separating from the rails. This was a minor separation about a cm and now it is growing.
I have laid more epoxy and ptex into this board than my 5 year old salomon's entire lifespan (and I ride that thing hard).
We all have our opinions about boards.Maybe mine was just a lemon. But since most of the damage started from where the rails end and at the nose and tail, (as you say not a big deal), I am putting 1 and 1 together.
Now I am not saying all GNU boards are bunk however I am just stating that this is obviously on the lower end of their product line.
I was talking with a tech from a board shop yesterday and he mentioned that GNU are just cheaper versions of lib tech. Merv Manf. puts lib tech features and design in these boards so they can get their technology to the budget oriented market share.