I don’t like the idea of a G1 assualt on Caucasus either. It overextends the german armor too soon.
Caucasus is key to Germany breaking Russia’s back. If the Germans manage to have a Med. fleet on turns 4 or 5 they can land 4-6 inf in Caucasus. This inf can be supplemented by inf pushing up through Persia from Africa to hit Caucauses on the same turn. The resulting German stacks on E.E. and Caucasus can turn Karelia and Ukraine into a Deadzone for Russia, by forcing Russia to commit hvy forces to Moscow defense. If Russia attacks Caucasus, then the E.E. stack will take Karelia. If Russia doesn’t attack, then the combined stacks will take Karelia next turn, or worse, the E.E stack will advance toward Caucasus, while the German fleet continues to pump inf into the stack. Most fun.