What would be the best possible outcome for both the Western Allies and the Soviets if this were launched? And which would be more likely to occur, and under what circumstances?
IIRC, an idea of both offensive and defensive version was exclusively British and inspired by WC who would benefit politically from a major operation starting just before the elections (with all my deep admiration of WC, he was hardly a military genius or outstanding strategist and his ideas during WWI and WWII were not always the good or realistic ones).
The goal of the offensive scenario being "square deal for
Poland" (which probably meant enforcing the recently signed
Yalta Agreement). Taking into an account a clearly expressed absence of the FDR's interest of spoiling relations with the SU over the "Polish issue", it was so unlikely that the US would go along with such a plan that the British Armed Forces' Joint Planning Staff considered it "fanciful". If anything can be deducted from Ike's "Crusade in Europe", he would be against such an adventure by more than one reason and and idea of using the German troops could cause enormous political scandal.
BTW, even the "Polish issue" at that point was hardly a valid political excuse: Yalta promised that the provisional government should "be pledged to the holding of free and unfettered elections as soon as possible on the basis of universal suffrage and secret ballot." Which meant that the elections would be unsupervised and under control of the pro-Soviet Lublin Government. In the words of Admiral William D. Leahy, the language of Yalta was so vague that the Soviets would be able to "stretch it all the way from Yalta to Washington without ever technically breaking it." In a reality, the
letter of Yalta Agreement was hold: the reorganized government did include the non-communists (I wonder how and when government in exile became "democratic": pre-WWII Poland hardly was a Jeffersonian democracy) a Socialist,
Edward Osóbka-Morawski, became Prime Minister and Mikołajczyk became one of 2
Deputy Prime Ministers (and Minister for Agriculture). Of course, as Stalin put it, "it does not matter how people are voting; what matters is who is counting the votes".
As for the defensive version, IMO, the SU was not in a position to start a new major war both due to the economic exhaustion and the need to "digest" the acquisitions in the Eastern Europe so the whole idea was too much on a paranoid side. The American troops had been in a process of withdrawal from Europe but the Soviets desperately needed the manpower at home to start rebuilding their economy (besides a need to send 1.5M to the Far East against Japan; thing much more important to the US than the affairs of Poland or Czechoslovakia).