Pgrens with vet cannot "handle upgraded rifles or 5 man Tommies easy" with similar vet. They get demolished much like any other infantry squad. Double bar Vet 3 rifles / Double bren vet 3 IS are undisputedly the strongest, most cost efficient on-map squads in the game.
Don't invest in an LV and try to push with it into shrek squads; they're designed to counter that kind of play. Go for an AAHT/Quad and suppress the shreks at range, they'll have no counter to it since they have to ATG.
As for the 'muni surpluss', between 100 muni shrecks, 60muni "bolster", 60muni LMG42, grenades, etc. ost isn't floating a lot of muni early game.
Why don't you open up testmod instead of talking trash? Vet 3 pgrens more than stand their own in most engagements against 5 man Tommies, unless you're sitting in cover at long range with perfect conditions pgrens will win. That's not even factoring in the nuke grenade that's a copy of the commando one
Then there's stuff like their accuracy on the move that's some of the best in the game helping for wipes. Vet3 rifles come close with double BAR but they're going to be seal clubbed until you fork out 120muni a squad.
Someone would think pgrens are ostruppen by the way you talk about them