Lately, I've been been looking at games employing the old Universal Table. That is derivates of TSR's Marvel Superheroes Roleplaying Game, sometimes called FASERIP, which is potentially confusing as one of these derivatives is name FASERIP. I haven't made an exhaustive study of them, but I have gotten a feel I think for what the authors were looking to update or add to them.
Interestingly, the Karma system is tweaked in all three of them, suggesting the way it works in the published editions is high on the list of thinks to fix.
Anyway, here's my brief rundown:
FASERIP: This one hews the closest to the original. Mainly it seems to switch out the original powers and their descriptions for a semi-"effects based" system system derived from Icons. It also changes advancement to be based around "milestones" and the pushing of abilities. I hear the character generation system is based on Golden Heroes, but I'm not familiar with that game.
Astonishing Superheroes Book 1: The Basic Rulebook: This is the newest of the three. In fact, it's not really complete yet, though the the published books and a Beta of the second book give you enough to actually play it. It occupies a middle position of the three. It's changes/innovations include adding a mental/spiritual health score called Resolve, and rolls for social interactions like persuasion and the like. It's Karma system cuts character's initial Karma by 10, but makes up for it by more greater rewards based around character personality traits/ideals/ believes. It's power system is a looser than FASERIPs, though perhaps not looser that the original games, other than drawing attention to this looseness by discussing how you would create new powers.
Marvel Superheroes Nth Edition: Is a bit like a mashup of Fate and MSHRPG with a bit of Marvel Heroic Roleplaying in there. Like more than one MSHRPG "heartbreaker" or fan-tweak it adds more ability ranks (more than most others I've seen) and a critical failure level on the universal table. It also adds more attributes, making them more specific in their focus. Talents also get expanded ranks. It adapts the "Four Actions" of Fate, and ditches Karma entirely for a system of Drama Points based on invoking Distinctions, traits that define the personality and backstory of characters. Like ASH, it adds a mental/spiritual stress track (Sanity) and rules for social interaction.
Nth Edition has some interesting ideas, but there's just too much there for me. It's like it wants to be a crunchier MSHRPG and a more narrative one. I'd prefer it picked one or the other. FASERIP is probably the game for those that just want a cleaned up MSHRPG, but really, unless the author's concerns are exactly congruent with your own, it seems like it's playing with someone else's house rules. Of the three, Astonishing Superheroes seems like it overall balances putting some modern innovations into the game without making it alien to the people who love it.