Haven't read all but I've been to 6 shows in 2017-2018 and it really depends of the organisation.
In Werchter last year I was frontstage, stuck to the barrier (there was no EE, just golden circle), arrived very early (not far from my home) and it was possible to move but it was a festival and it started early.
In Paris last year, with all these stupid people, I was front, just behind the EE but I had to move back when they sing CD because I was too crushed.
This year in Gelsen, I was just behind the barrier and it was possible to move to take a drink for example.
In Nijmegen I went with my son this year. No problem, we were at about 2 meters from the barrier and we have arrived during Gojira, at 17.40, not in the front but in the Slash side at about 5 meters from the catwalk. It was a nice crowd, you could move and go back after.
Overall now, the gnr fans are older and some of them (like me) come with their kids. There were some at each show. So they are generally quiet, except in France where all the assholes convine a meeting.
For the Merch, it depends. In Nijmegen, there was no merch outside. So take care... I think if you want the barrier, you have to arrive very early and don't buy merch but run to the front. Remember that lots of time, there are people who wait for 1 day outside...
Sorry for my english.