Is the 251 really OP? Just cuz it was popular (like ostruppen) doesn't mean it's OP. But I'm not surprised that this statement is coming from you, katitof. "Nerf whatever is popular for Ostheer. Because God forbid, Ostheer is allowed to win games."
Would soviet M5 be OP if it arrived early to support current cons and penals?
Same deal if grens got performance buffs, especially as insane as stock 5th early game.
You want to play brits, go play brits, don't mold axis into them but without all the downsides.