I played this game on KR and TW servers back when Mushin Fl.8+ and Spiral were the end game, respectively.

BNS is a lot easier now.
Every class has gotten a minor to major increase in dps at all levels.
End game is currently slated to be the 4 Blue dungeons, and Poh (6man and possibly 24/4 man versions) at release.

There is no Mushin Tower (though it would probably be added shortly thereafter.)
Story ends at beginning of Act4 (aka you need to go to Mushin Tower to continue the story.)

From 300/250ms to <75ms ping, your dps literally doubles. That’s just the way the game is coded, (it doesn’t have auto-queue smart casting like most modern MMOs.)
So at least for the first few months or first year until we catch up to current day Korea content as of September 2015, BNS NA will be incredibly easier than what most veterans were used to.

So Blade-Soul really don’t need to give a shit about class balance (we’re the only server that will have limited end-game dungeons and gear, but with updated skills) as you will be able to Duo any content meant for a full party without much difficulty once you’ve learned the encounters in the NA release.