This is my big concern with Obers they arrive to late and are usually up against vetted infantry, is shifting obers to T1 to much of a game breaker? Would the option of having a shrek or a lmg be agreeable?
At the very least would open T1 builds into the meta, good synergy with being able to heal your troops and have a decent mix of AT and AI infantry supported by crewed weapons. Or a less versatile infantry mix supported by light vehicles with a T2 build, meaning a high risk, high reward payoff with vehicle rushes.
I don't think so balance-wise. At this point its not much different than Penals, PZ Grens, or most Call-in Elites. Cost will always limit you from spamming them early so yeah... you could always allow Obers to be built but lock the MG34 behind T4 so they aren't *too* good early on. Though Mirage's method is a bit more conservative.
In case you didn't know what Miragefla does - he decreases price of T4 building and then requires a munitions upgrade for flak gun and an additional unlock for vehicle production - allowing you to unlock Obers faster without the cheese of fast flak lockdown.
I suppose another option would be to allow Obers to be built from HQ but require either T4 OR Med Truck + Mech - that way you don't miss out if you go T1 -> T2