But that's not what a Recoilless Rifle does, CoH1's RR's were a work of fiction. Actual Recoilless Rifles fired modified artillery shells, and were used against infantry, unarmored vehicles, and field fortifications. Essentially it's direct-fire pocket artillery, something that unless employed as it's own unit (With setup like MG 42), would probably either be UP, RNG, or OP. Consider this, people hate Rifle Grenades, but a Recoilless Rifle is basically shooting Rifle Grenades at the rate of a Panzerschreck.
While Recoilless Rifles did have HEAT rounds, they were very underwhelming, vastly inferior to the Bazooka, and Anti-Tank wasn't the purpose of the RR. Having an RR with HEAT rounds solely as a better Bazooka is like calling in a StuG E with HEAT rounds to act as a better StuG G.
I think the concept of an anti-infantry zook could be balanced if it cost enough munis. Stuff like croc, t70, bofors, etc already do a number on infantry. If it was doctrinal, took maybe 120 munis, and 2 models out of a squad it could be balanced.