3. Lots of games use skill-based leveling to much effect.
Technically the first game to use it, I believe, was Wizardry, which had traditional levels and experience, but the sort of stat gains you got depended on what you did in battle. You could also lose stats. And it was namnogo punishinger than FF2 ever was.
But yeah, skill based levelling systems predated SaGa.
Persona -- Though it's probably the worst of the series (it seems to get progressively better, though some ppl swear by the import P2 Innocent Sin), it's an excellent game to try out.
I liked Persona more than Eternal Punishment in some regards. Both games sort of fail at dungeon design so I won't be discussing that, and I do tend to think that Persona 3 is the best in the series by a sizable margin for a large number of reasons. Anyway, stuff I liked a lot about Persona 1:
More characters: Fairly minor point, but P2: EP only had Nate or Ellen, whereas in P1, you got to pick betweeeeen Chris, Brad, Alana, and Ellen to choose from, in addition to the other four characters.
Persona Fusion: From what I remember, in IS, you had regular SMT style fusion, but in EP, it was like "Collect X number of cards to summon a demon," and I didn't like this as much as what P1 and IS had.
Battle systemy stuff: Weapons were useful in P1, and everyone gets guns AND melee weapons which can both be useful as they act differently. Weapons were not useful in P2. Also maybe it's just me but P2 seemed to have a higher encounter rate. Additionally, I actually liked the "range and position matter" thing in P1. Also, P2's interface bugged me a lot here. It's like in Phantasy Star 2, where the default command is "Start Auto Battle" and you have to sort of go out of your way to enter commands. Battles tend to last forever in both games so whatever.
Points about the translation I feel I should mention: From a grammar and writing standpoint, it's pretty much on par for the era and there's nothing outright Breath of Fire 2sian about it. Yes, it was Americanized a bunch, but this never bothered me. Your mileage may vary. I will say that I found EP's writing to be incredibly stiff, although this was, apparently, just EP, and not the translation, as people that played IS tell me it had better dialogue or something. chaning the spell names in P1 was seriously annoying though, especially when you get used to the regular naming system the rest of the series uses.