More on-topic, I've heard 2002UM's netcode is a step back from NGBC, but I've also heard that it utilizes roll-back. Did NGBC also do that and I just missed the memo? Is this the first SNK game to use roll-back?
Elaborate on this roll-back please. Is this a coding term?
I'm no expert, but my understanding is that:
Traditional netcode uses lag in order to solve the problem of slow connections. For many genres, this creates the most seamless gameplay experience.
For fighters, it obviously creates a lot of problems. GGPO's big innovation was to replace lag with "roll-back." So if a connection speed suddenly drops, the game simply pauses, or even goes back (i.e. rolls back) to a moment when the players' were synched up. It can be a bit jarring, but typically lasts only a second or so.
I'm sure someone more knowledgeable about it will come along to correct any mistakes I've made.