no they come at the same time
I don't know exact digits, but let's imagine that it's right. What you will get in that case? German "sherman/cromwell" that have the same stats and abilities as allies, and don't have any strong sides against.
You just cutted off your own hands with that decision. Every armor combat between your and ally medium become very danger for you, you got 2 almost equal mediums. Who will win in battle if opponents have equal skills?
But if you prefer light armor to other bonuses (accuracy, abilities) why not? When USF and UKF every game will be use M10 against you, soviet su-76 with spam t-70. You maybe understand that more "old" P4 was better than new "modern".