The ostheer mortar has a slight edge over the usf mortar. Ostheer also has pios for los. Every good usf main ignores the usf mortar in 2's and up. It is only useful when your opponent does not build mortars.
I Mean.. I know I'm not a great player but the smoke against Ost mgs alone make the usf mortar worth it. It's not a game maker anymore it's a force multiplier. People look at ANY unit that requires micro and automatically write it off. It's not the set and forget wipe machine it was but it's not trash either. It's job is to provide smoke and garrison denial without a fuel cost as an alternative to grenade techs. It does that.