LMG42 is a very nice upgrade, but that's for 60 munis, brings you down a flamer, cuts your mobility dead and hurts your chances to faust the incoming Clown Cars. Not one single ability in the soviet arsenal cuts their mobility, in fact, they tend to boost it.
Hit the dirt disables movement for a while, i would call that "cuts their mobility" and as far as i can remember the LMG is the only upgrade/ability that limits your mobility.
Shock troops grenades costs 45, guards grenades costs 45, flamer costs 60, so your point about the "expensive rifle nade" and how soviets abilities are all cheaper is also false.
I like the way this discussion is going i think there are a few good points, so please stop this hyperbolle bull Sh%t and keep to facts are people will stop listening to the few good and valid points made.