I can't help wondering if you're right, Colwyn...about the potency of the Russian army in 1945. They definitely had good tanks, no question, although they were somewhat crude compared to the competition. The JS-II Stalin tank was even much more formidable than the T-34. And you are right that the last generation of Russian fighters (Yak 3, Yak 9, and La-7) were darn good little planes...plus they had the premier ground attack plane of the war, the Sturmovik to destroy enemy armoured formations.
Maybe they would have rolled over the western Allies...
My impresssion is that the American Pershing heavy tank and the British Centurion were superior to any Russian tank of the day, but there were a relatively small number of them available at that point...most American units still had various versions of the Sherman, and it would have been outclassed by the Russian armour.
If you are correct, then the main value of the atomic bomb was not its effect on Japan (which was actively seeking a negotiated settlement and an end to the fighting anyway in 1945) but the fact that it kept the Red Army in check.
If so, I'm glad it happened that way.
Patton, who was definitely the fightingest general the Allies had, couldn't wait to get at the Russians, and was certain he could whip them, but Patton was a born optimist. He may have been wrong. I'm sure Zuikov was equally optimistic when it came down to it.