PPSh and grease guns don't differ much in their stats. Moving affects them both similarly, losing about 25% of their static DPS.
Situation: vet 5 pfusilier behind green cover. Fully vetted cqc squad approaches from 25-30 meters and stops at 5-10.
The results are confusing.
6 men ppsh cons perfromed better then un-upgraded cav rifles, Assengies and mp40 volks. 5 men Airguards were just better and were often winning that engagement, ppshcons could win. I think if you add a sprint, ppsh cons will definitely win in this AFK situation.
So AFAIK airguards RA is similar to assengies + ppsh is very similar in terms of dps to grease gun. I did around 4-5 rounds with each squad. No idea what was that, actually. Also did a run with UKF officer. He also did win the fight.