Thing is with 1 speed IV and a sassy nature it outspeeds all Conkeldurr Mach punches, although you wouldn't want to face it because of the removal of flying type for roost.
You also outspeed all Azumarill.
The only thing you don't outspeed are most Extremespeed users, such as Dragonite and Lucario, and the rare vacuum wave Toxicroak. But there's no room to invest in speed, really, since murkrow is going to need all the HP/defenses it can get to survive as a perish trapper, so you wouldn't be outspeeding them anyway.
I'm going to give it FeatherDance, Perish Song, and roost, definitely.