Did some testing with the calculator and changed a Niles to have the same stats as Faye. I was a bit worried about her being able to threaten Linde or Hector, but she'd get doubled and killed by Linde with no chance of counterattack even with her high Res and Linde not in Desperation range. And she'd do like 1 damage to +DEF Hector.
Alm is even less threatening. Sure, he won't eat counterattacks from Hector, but he'd need 2-3 turns to kill. In that time he's probably been nuked by Linde or one rounded by Lucina about 5 times over. I'm not sure what he's actually dangerous to. Edit: I guess he'd be great against Swordbreaker/Quick Riposte Nowi.
Now, these skills on OTHER units could be nasty surprises, especially since I rely heavily on baiting out the first attack to wipe out one of their guys. On a unit that isn't slow as shit, the Firesweep Bow CAN double and that's when it's scary.
But I'm not rich enough in 5* to even consider doing that kind of thing yet. I do need to start preparing to see them in Arena though, I mean I've seen Distant Counter Bunny Chrom and equally silly things.