Much like almost anything in the game, they are often best fielded in multiples. One FMC will get focused down and killed. Having two or more will ensure that at least one or two will survive till they get into combat.
With the changes the the FMC rules, they can no longer charge after switching movement modes, making turn 2 charges much harder. If your FMC is shooty, I'd keep them in the air. As for one that assault, I cannot say. Swooping them turn 1 will keep them safer from enemy shots, but opens them up on turn two as they have to wait till they charge.