I'm surprised this debate is still going on, as I have trouble understanding the concerns the MP'ers are voicing. Personally, I DON'T see the problem with boosting an individual country that persistantly performs poorly under AI control. ANY country does well, usually exceedingly well, under human control, so what?
With the general idea of MP being initial starting balance between the playable countries, I think the BEST test for that is the AI's performance, with few exceptions. What should be seen with an ideal setup is that any particular country under the AI collapses, stays about the same, or grows much larger in about equal amounts across many games. If this is true across the major MP playable countries under the AI, then you know a good balance has been achieved in the possibilites and playability of the countries, with few exceptions (such as Ireland or Portugal). If a AI controlled country in SP CONSISTANTLY fails to perform at all, it doesn't matter if they can excel with a human player in SP, the only logical conclusion is that they have a disadvantaged start, and thus do nothing to enhance MP without some kind of added handicap.
It's all well and good that most people can do amazing with, say, Bavaria in SP, but I can tell you just by looking at the start up that in a MP game, one of the first things I would do as the Hanse or Hungary or Burgundy, etc. would be to gang up on Bavaria and in one war completely crush and annex them, just as happens in SP. It just makes sense, from a tactical, strategic, and economic standpoint.
Honestly, I fail to understand how a country that gets crushed every game with the AI could be a viable country in MP at all WITHOUT wholesale boosting (excepting colonizers). And I especially fail to see that we yet to suggest changes for any country falling in this category. This is why I can't believe this thread has caused this much discussion over what I see to be a moot point.