I could stand perhaps 25-50% more provinces on the existing area of map, if this would lead to something meaningful.
PE has a strong point regarding huge number of provinces not adding to playability however. I cannot honestly say I prefer HoI3 to HoI2, and some of that reason is the extreme number of provinces and units.
In CK there were lots of situations with log notes like (approximately) "County of Somewhere has joined the war on you" without having any clue where Somewhere is. Adding provinces will increase the frequency of this kind of situation.
As a side note the search function was annoying to use because it presumes perfect spelling including diacritics, so it could be very difficult indeed to locate the opponent in many a non-sensible war.
PE has a strong point regarding huge number of provinces not adding to playability however. I cannot honestly say I prefer HoI3 to HoI2, and some of that reason is the extreme number of provinces and units.
In CK there were lots of situations with log notes like (approximately) "County of Somewhere has joined the war on you" without having any clue where Somewhere is. Adding provinces will increase the frequency of this kind of situation.
As a side note the search function was annoying to use because it presumes perfect spelling including diacritics, so it could be very difficult indeed to locate the opponent in many a non-sensible war.