Meg eventually becomes a tank rivaling characters like Aran and Jill, and she's even dodgier thanks to her high Luck. Her Str/Def growths are lacking, but her bases and promotion gains keep those somewhat competent. It's not like her durability really struggles, save for the slump that is Part 1 (where every other one of your 1rst tiers still struggle). If you train Meg seriously, she can be really good in Part 3, and that's more than what Ilyana can say. Her one chapter at the end of the game hardly matters, let alone when the most optimal way to finish 4-E-3 is to rush it.
People really underrate Meg because she comes somewhat underleveled and gets doubled in her starting chapter, but then she also has a ton of availability to work with, and doesn't leave the team with the Exp you're taking. I never found her Mov to be an issue, since maps aren't a huge open field or anything.
I have a lot of trouble seeing that in HM. I started playing the other day again, and I can barely get Edward, Nolan, Aran and Ilyana to lvl.16, 17, 13 & 17 respectively. Micaiah is lvl.10-12, and I just gave up on her so the others could get Exp. And I was taking my time, too. lvl.20 for 2 characters by 1-E is generous, let alone 3 or even 4.
Edward is another character that's really underrated. He has a lot of time to train, and he's pretty vicious after you do get past his Part 1 slump. He's one of the two only characters that can use the Wrath/Resolve combo, and access to Cadabogl and a fast support with Nolan makes him almost as dodgy as Zihark with double Earth, but with far better offense. He's one of the best characters to kill Ike.
Their Spd caps don't really become an issue until Endgame (save for characters like Rhys, who have 30 Spd cap). I mentioned earlier, in the Gatrie topic, that characters with like 31 Spd (Gatrie and Oscar) can double up to around 4-E-1, and that really enough to get you through most of the game. Caps aren't a problem as we once thought they were, and we ought to recognize that.
Fire Sages, in particular, they have access to Rexflame, which gives them +3 Spd. A Sanaki with capped Spd and enough Str (not hard to reach with some BEXP) can actually reach 35 Spd, if that's a concern.
She just need to take a hit from any enemy that isn't a Warrior. I've done it a couple of times, and it works well in practice. It's actually easier than Part 1 Micaiah, ironically.
No, they do pretty well, assuming you have trained them (why would you bring them to Part 4, otherwise?). Soren and Callil are the most likely ones to pull through, but Ilyana takes a lot of work to get her there without getting lucky in Spd or favouritism of some sort.
She has a bad start, but a ton of availability and resources (which she can use well) to work with. She's honestly not that much worse than the other unpromoted units, since they're all getting 2HKO'd. She does get doubled in her starting chapter, but I also know she gains Spd fast enough to get out of that and start taking hits later.
She's a solid Part 3 frontliner, and it's sadly more than what Ilyana can say.