Okay. The "merging" Clover is so fixated on is actually usually referred to as "consuming", the descriptions imply a noteworthy size difference, and at the end of the day Clover's evidence is using selected interpretations of single words whose definition doesn't even match what he says, and his interpretation clashes with the more used word "consume", which unlike split and merge actually does have pretty strong relevance to size. The fact that the demon world contains both finite and infinite dimensions, as well as dimensions stated to be diverged from time, within itself as lesser parts, including a duplicate of the human world, only further exacerbates this issue. Hard to call them equal in size when a dimension that's the same as the human world is contained as a small part of the demon world.
2-C is fine, but we should stick to that. No need to include this exact equal split thing which is clearly just riding on the coat-tails of the 2-A downgrade. Although if implemented it would mean upgrading several upper mid characters to 3-A which would be very shaky.
Update: Clover, are you just planning on doing the 2-A to 2-C adjustment, or are you meaning to upgrade the 4-As to 3-A? If the latter is happening it might be messed up not to mention it in the OP.