FM Paul Heinrik: the Germans were suffering from the prolonged strategic fight by most fights in CMBO. Tungsten was just too hard to come by.
re: Sherman vs. PzIV: you are noticing that the finer-point differences make picking a "best" tank rather tougher than just armor and gun! The key is to exploit the weaknesses of your opponent's armor. If he's using turretless assault guns, those flanking Stuarts and Shermans are gonna be great. If you want to slug it out at range, better hope you have a better crew.
Use what advantages you have, and minimize the risk to the weaknesses. In US armor (to me) that means get in to a knife fight and keep using shoot-n-scoot tactics. Even with heavier German armor, keep the fight mobile, and don't get cocky that your armor will protect you. By war's end, the gun factors had nearly outpaced armor factors, and you get the "hammers vs. eggshells" theory.
Crew factor seems to be the most decisive factor in my armor experience. 3 green tanks do NOT make up for 1 veteran crew IMO. Now there is a limit to that, and numbers will grind down your forces. Even regular crews that outnumber you by more than 2-1 are bad news.
Another strong factor is range to target. If I have a tank that has engaged a certain ridge or other BP, repeat shots to that locale are much more accurate. Remember this factor when you are deciding where to roll out that reinforcement tank. If you are ranged in, find another way 'round, because you will not get steel on target as fast as the tank that just shot up your wingman.
I agree that having those expensive Panthers shot up by Stuarts is frustrating, but strive to minimize his opportunities to get around your flanks. Also, since German armor is usually more expensive/rare, an Allied player will occasionally make mistakes by trying to flank that big cat, and fall into inexpensive AT gun or panzerfaust ambushes at the flanks.