Interesting thoughts. I feel like everything above is why I think it’s actually a pretty good rule where both sides have benefits and detractions to signing or not signing.
To the point above about Eastern Poland. If the Pact isn’t signed, what’s to say that the German player doesn’t wait to use it’s Lightning War ability until it’s ready to swallow all of Poland in one turn? I think there are enough ways around that to make any British buildup avoidable.
Likewise, to the points on Romania, let’s not forget that Romania’s military is no so unsubstantial. Frankly, if I’m the German player, and the Pact isn’t signed, and I see the USSR preparing for and then attacking Romania, I’m seriously considering waiting for the USSR to waste their troops attacking Romania and then declaring war on my next turn. The USSR isn’t that strong earlier in a game without more IPP. This obviously depends on how a game is going, but I think there’s a lot of room again for a German player to anticipate this move and lay in waiting to exploit the loss of Soviet units in Romania before sending a counterattack.
If the goal for the USSR is to have a bit of money and avoid a front against Finland, why not just ignore Finland then? Sure, you sacrifice 1 IPP with a signed Pact. But you still have 1 IPP for East Poland and 1 IPP for the Baltic states, not to mention the 3 IPP for signing the Pact, for a total of 5 IPP (not including the free tech roll), as well as keeping Finland neutral. If you don’t sign, you get 3 IPP for taking Romania, maybe 1 IPP for the Baltic States, and 3 IPP for Finland if you take it all, for a total of 7 IPP. If you add the free tech roll, this comes out as a wash IPP-wise, but you’ve also now expended IPP on troops lost in your invasions of Finland, Romania, and the Baltics. But yes it is noted the 5 IPP that the German’s get each turn as well if it’s signed.
Even then, the USSR player may not even get the 1 IPP for the Baltic States, as if they take Lithuania, wouldn’t that trigger the Allied ability to declare war on the USSR, as Lithuania is a Neutral Power that doesn’t border the USSR? Maybe that rule has been errata’d, I seem to remember a discussion on that very thing somewhere on the boards before, but can’t remember what the decision was.
I guess I just see a lot of upside to signing the Pact, though can also see reason’s why you might not want to. I think it probably has to come down to situationally in each game. It frankly probably depends on what German troop placement looks like, and if the USSR player thinks they can correctly guess what Germany’s next moves will be.