Pioneer 5-man is already more than enough for repair speed, having PzGrens also repair is overkill as there would already be better squads for the job available earlier and for cheaper.
Methinks the best way to keep the combined arms ability is to replace a lackluster ability with the Panzer IV F1 that emits a passive combined arms that applies to Panzergrenadiers. It also adds late game to the commander. I would happily give up 250 to see the PzIV Infantry Support Tank.
All in all though the Panzergrenadier stuff is uncalled for and doesn't seem to fit the infantry theme. Panzergrenadier changes tend to imply a mechanized theme: why would an infantry doctrine have better coordination with vehicles than mechanized? Transferring its ideas over to other core infantry units is the more elegant solution. In my suggestion, all of the Panzergrenadier changes have been incorporated in some way within other units with the exception of the field repair, which like I already stated is overkill.
Ostheer is a very repair deprived Army, up until this point their sole repair capabilities were in the hands of the Pioneers and that was the end of it.
Looking at the Soviets and the amount of options they have to repair in terms of commanders makes me think that there is nothing wrong with giving options to the player.
Many people have also said that Mech Company is also overkill with the amount of light vehicles it now has and it's entirely out of the question to see all of them in a 1v1 game but that's again left up to the player.
So all in all the utility given to the PGs in the end doesn't hurt anyone really and just provides the player with some more options at his disposal. As for how it fits in the doctrine, PGs are still infantry so I guess you can say that they are entitled to get something out of the bargain, doesn't matter if they're supposed to be supporting tanks. If we're going into semantics they're also supposed to be either motorized or mechanised, meaning only coming on the field in either trucks or Halftracks which they don't.
But I agree with you about the F1 Pz IV, if you go back to about the middle pages I think you can see my suggestion of replacing the Arty officer with it as well for some additional late game presence from the commander. I had the Tiger as a suggestion before that but the F1 made more sense because it was a dedicated infantry support tank, similar to the StuG E but not exactly, plus it further added something new to the table.
Speaking of the 250 tho, would be awesome for Urban Assault Panzergrenadiers to come in it as a mechanised combat group lol.