I may be drunk, and not thinking through it, but how bout just not showing the #'s in each arena?
I've heard people support that before, in a sense, it's kind of a slap in the face to the player base. If I am a new player and I log in at 12:30 in the day and orange is closed and blue is open and I go to blue and say 14 players on, I'm going to think this 'MMO' game sucks. People like to see how many players are online, gives it that community feel.
I like this wish though and it would give the community a way to balance the arenas themselves. Of course, the ultimate issue with the game is that most of the time, there aren't enough players on to fill up two arenas at once to the point of minimum gameplay sustainability. I think the real trick to dealing with the cap problems is getting about 2000 more europeans to sign up for this game, which would keep both arenas populated 24/7. Then, putting it into the communities hands to help balance the two arenas would become VERY feasible. How to do that? I'm not sure about HiTech's advertisement efforts in Europe but if it was somehow possible to attract more from across the ocean, HiTech Creations would be on top of the world.