Well, I'm not very fond of letting Prussia lose as well since I'm fond of Britains gains in that war (many of which will be reduced in this TTL).
On the other hand, if I've gone this far get the Stewarts on the Polish throne, I'm not about to let Frederick [not the great in this timeline] and his unhealthy thoughts surrounding Poland come through.
Germany might benefit from a lessening of Prussian militantism...
Hold on, my good man. These are the Stuarts we are talking about. What in their eventful history as a royal house leads you to think that Frederick II of Prussia would present a problem for them at all?
Actually, I must admit the first time I read your precis describing this timeline I thought: "Stuart Poland, no Prussia...is this the story of how Russia realizes its natural western frontier is the Rhine?"
Once again, I kid.
In all seriousness though, I don't suppose I have to tell you my thoughts about timelines that imagine different courses for Germany in this way.
I actually am looking forward to reading this as a timeline, if you choose it.