While I can't say he was phenomenal with me, I felt Eliwood still carried his weight. He's mounted, so he can get places much faster, and he has lances for a secondary option and Javelin/Spears, and Durandal gives him a hard hitting option. Those three together gave him something to keep him moving, even if he could fall behind the faster Lyn and tankier Hector.
As for Roy vs. Micaiah, both are not good, but at least the latter can heal, attacks the weaker stat and can actually use her promotion for a bit longer.