Star Ocean 4 - Completed on Universe Mode, party was Edge/Faize/Myuria/Bacchus. The phantom army ended up as the hardest boss fight, followed by Tamiel, the final boss, and Armaros Manifest, probably in that order. Bit of a grain of salt needed since I was probably somewhat underlevelled midgame. The more battles one can skip before benching Lymle, the better. The big surprise was how competent the first form of the final was, which I found roadkill on Galaxy but was about as scary as the real fight this time, aside from lower HP. I'm now planning to tackle some aftergame stuff, though not sure how much before I get bored. I usually do enjoy some Tri-Ace aftergames though... often better than the maingame! But I have less patience for such things than I used to. Not sure if I'll start using different PCs now or what.
Edge - He has Healing, which is good. Pretty damn unimpressed with him as a fighter though. Most of his better moves knock enemies around in weird ways which is bad for team play; the ones that don't are weak. And in general the game doesn't like melee fighters much. He's somewhat durable which is nice but not really enough to notice. I'd probably be better off benching him for Lymle or Sarah.
Faize - Yay! So Faize is a pretty bad PC, think we all knew this. Basically, take Myuria, and (a) drop her Magic by a bunch, (b) take away all her support spells and replace with Antidote, and you have Faize. I think his casting speed might be slightly faster but if so it's subtle enough I'd have to test it to be sure. Fortunately ice spells are the best, and Stone Rain's not bad either. His real problem is his weapon selection; double-digit INT at most from everything in the maingame except one weapon from the colossem. This puts him way behind the other mages until you get that, and I foolishly assumed I'd be able to get something better from IC or whatnot so I didn't get it until the final dungeon. In the final battle, and only the final battle, I gave him the Laser Weapon, because Myuria was needed for heals which left him as the best candidate to deal damage with Mindflare Ice Needles. Once the boss picks up Divine Wave and particularly Dawn of the Cosmos it just gets too punishing to fight at melee. (spoiler) Also Faize dealing the final blow to himself is kinda meta.
Bacchus - No new revelations on Bacchus, but he's very good. Great set of moves, even if every one of them has a problem or two. Tanky as hell. Emergency Healing is nice. Black Hole Bomb is sooo good at controlling randoms even on this mode where it fills up their rush gauge quickly. I also ran into the Kokabiel refight in the last area and that move destroys her which is good because in the real fight I had no particular counters to the fight (she resists all non-dark elements, dark symbols are bad and Bacchus' best weapon by far at that point was lightning) and was thus forced to use Edge which is an awkward/slow process (fortunately it's not a fight that's too powerful offensively). Galvanic Shock is really good what it does, a bit cumbersome but piles out loads of damage (makes Armaros Manifest explode). It's the best way to deal with the early stages of the final boss because of the random stun, later on it just gets too difficult to set up though. I also got good milage out of Termination as an area-of-effect crowd control move, particularly after picking up Berserk, although it gets largely shelved once Black Hole Bomb Sphere shows up.
Myuria - Again, nothing new, she's good. She's mostly about firing off Ice Needles spam off great casting speed (also Deep Freeze freezehax, or lightning crowd control) but then she picks up Fairy Healing and Restoration for no real reason and is arguably the best healer because Sarah is so much slower. Freezing is even more useful in Universe, the rate didn't seem to drop much. Final dungeon has a decent number of freeze-immunes but who cares.
Compared to last time when I used Sarah and Reimi... Reimi was certainly missed for Kokabiel and the final boss, but otherwise I think I may have overrated her somewhat in the past? The stat topic kinda taught me there's not much she does that Myuria and Faize-with-real-weapons (and perhaps even Arumat?) can't beyond that extra elemental control. Still that long-range damage niche is one you can never have too many of, and she's the best PC at it for a while. Sarah... I've noted before that generally I think the game gets easier if you use more healers. Even on this playthrough I used her in a few fights (Phantoms because lol AI-controlled fighters there, so I subbed out Edge, and Armaros Manifest I subbed out Faize, and I used her for an underlevelled quick sub-in-and-heal in a few other places, particularly bosses) which says some good things about her, even if she has her problems (no Fast Cast means she falls behind as a healer late).
So yeah. Current plans are to open a bunch of treasure chests for aftergame skills, pick up Fairy Star (though I'm not sure who to give it to), then tackle the Cave of Trials the Seven Stars.