Agree that Yang is a pretty meh choice due to shooting up in value on F7 while being quite blah F1-F6. Tellah might be workable, though. Not an amazing 1.5 but a versatile one, at least if you have MP healing.
+1 to Elincia in the Dungeon; I wrote a bit on her before:
http://www.rpgdl.com/forums/index.php/topic,1736.msg141315.html#msg141315She's a bit awkward on F1-F2 where her offense is bad but she's nigh-unkillable to make up for it. Still, without revival, she could theoretically get into a bad position of letting everyone else die then failing to solo. But yeah, she's pretty broken on F3 and F6.
I think there was a debate on Cthulhu before, and 3.0 is probably too pricy. Cursed Sword is a great way to get the team killed in the Dungeon where you can't exactly take it off, iS F5 anyway, and his drain game doesn't help so much without revival. He's a lot more vanilla F1-F4 where he'll be a bit of a drag. Maybe a 2.5?
Umi is quite possibly worth more, though. Siren's Call off good speed = totally awesome in the dungeon, and Keep Fighting is one of those great reset buttons to bail out of impossible situations. Unstoppable 1-turn stun + a damage boost is Millenia-lite, except much faster. Throw in some fast status for fun, some of which I believe could be set to MT (Rather than cruddy GT)? Yeah, thinking she's more like a 3.5, even despite the durability problems. If she gets a stun off then dies that's still pretty good for many teams.