I think the "barriers" depend on the players. I've heard of people getting stuck everywhere.
Are there any specific requirements for becoming a NM?

Well, what if you'd made it only to 1798? Grrrr...
I never could quite get to 2300 either (not even unofficially).

class B rating range (1600-`1799) has been proven to be the most difficult barriars to cross with that being said I just brok through class B a month ago and im now at 1684 after 2 tournaments (won both) wish me luck

Good luck. My only advice is to work on your weaknesses, really hard. That kind of discipline tends to be what it takes to get to really high levels of play. And of course, B level is very respectable in itself.

FIDE ratings
For top players, the most important rating is their FIDE rating. Since July 2009, FIDE issues a ratings list once every two months.
The following analysis of the November FIDE rating list gives a rough impression of what a given FIDE rating means:
- 5839 players had an active rating between 2200 and 2299, and are usually associated with the Candidate Master title.
- 2998 players had an active rating between 2300 and 2399, and are usually associated with the FIDE Master title.
- 1382 players had an active rating between 2400 and 2499, most of whom had either the International Master or the International Grandmaster title.
- 587 players had an active rating between 2500 and 2599, most of whom had the International Grandmaster title
- 178 players had an active rating between 2600 and 2699, all but one of whom had the International Grandmaster title

The main requirement to be an NM is that you have to be a real "people person."
Wow, there's actually a guy in the 2600s who isn't a GM? Who is this freakin' genius?!
However, a couple of years ago, Alex Lenderman reached 2601 FIDE and his GM title had not yet been approved.

The main requirement to be an NM is that you have to be a real "people person."
Wow, there's actually a guy in the 2600s who isn't a GM? Who is this freakin' genius?!
Before becoming a GM Ben Finegold had a rating of 2602 and when he actually became a GM he fell below 2500 talk about a contradiction
there seems to be a barrier at around 1800 but I dont think its a barrier as much as just absorbing information. A few players hung out at 1800 then bounced from there to a strong level (Fischer mentioned that he did this, Tal Shaked told me he did the samething)
I also think there is some mental thing about any particular rating that blocks people. If your at 1800 for instance your strength is a range +/- 200 points. once you realize that you can let go of that 20 point difference and just play....