When a coalition victory is achieved the other players get the reward based on their ranking of VP points. I think that the 3/4/5 coalitions based on the map size are a good number of players but is might get problematic indeed when a lot of players go inactive in the first 8 days and the biggest players have joined in one coalition. Still size is not the only thing but also skill. I'll chose skilled players for my coalition over players with a lot of VP every single time.

I have seen in the web cases for the big guns joining at the end, and it seems to me perfectly logical - especially in the big maps, when the alternative would be to drag play for many more weeks (with the result been even more inactive players from the smaller ones).

You can see it the following way: when a victory is not easily visible with the current coalitions setup, it is beneficial for all to split and finish the game faster. That way all the currently active players get a reward, which is extremely doubtful if the game had continued.

It is quite easy to imagine such "near stalemates" in all big maps (in Pacific map when there is one very strong coalition in Asia and another in US, in 100p when there are coalitions in Africa, America, and Europe/Asia, etc.). Then, a negotiation and a peaceful settlement is the easy way out.

I dont think like that, actually for the most part the biggest countries go at it in the 100. I think 5 players is just fine because of the begginning of the game.