With the recent nerf we've found that Sturmpioneers are no longer "Assault Pioneers" (Sturm = Storm or Assault in German) We've also found by graphs that they have an extremely narrow effective window against really anything before the effective ranges of other units between American Rifles and Assault Engineers / Shock Troops, really anything close quarters.
The patch notes showed that the close quarters or maximum damage range for Sturmpioneers has been adjusted to range-3 from the original range-8, while American Assault Engineers and Shocktroops were moved to a close range (read as max damage range) of range-10!
So what this tells us is that while any other SMG squad moves in to assault these former Assault Pioneers, they will have been in their max damage range 7 times over before closing in to facehugging range for 3 that the Sturmpioneers need to do effective enough damage to force them away.
This also means that if one so chose, they could have their SMG squads sitting back further and doing more damage than Sturmpioneers could! Because Max Damage at Range-10 > Max Damage at Range-3.