Here is a cast where the OKW pretty much picked the doctrine at ~20ish minutes just to have this ability. He did not build JLI, no goliath, haven't seen any use of "For the Fatherland" and of course no LeFH.
This is not uncommon for many doctrines, players can go whole matches without choosing a doctrine until the end.
The only effective use of the ability was when JibberJabberJobber got its 2 shermans at half health stuck blocking each others pathing and colliding with the munition cut off flag, and he still managed to save 1 of the 2 by retreating in time.
So, yes, it is an effective ability. If it were not, Scavange would have been more popular choice, then it is currently.
Scavenge would be a good doctrine if it didn't have an Ostwind 30 fuel away from OKW Tier 4 and 20 munition for the mediocre repair kits EFA cons get for free
A slower sector assault exists, it's airborne assault and it's a certified waste of munitions that 90% of the time doesn't even work
Are loiters supposed to be area denial or are they supposed to attack and damage and support an attack like il-2 attacks? Because if that's the case both are working as intended, as you'll need to react fast and move armor away/hit retreat to avoid considerable damage.
The unit per se is "fine"
The t-70 is an anti everything tank short of medium tanks, 444 and puma that obliterates infantry squads and it's insanely more popular, Zis is the best at gun in game and the t-34 can be easily accessed after tier 4, and on top of that Guards can soft cou ter light vehicles pushes, so the su-76m has no place among all the much better and safer options.
It should actually be nerfed to 50 range and lower penetration and have a 10 fuel cost reduction so it can be used as emergency AT vehicle