For us it is a very small time window between 6pm (when the cap kicks in) to around 7:30pm. The numbers in blue are likely to be around 20 to begin with then grow to 100 within the space of an hour or two.
If more people swapped from orange that is usually say 180 /100 at 6pm, Blue would hopefully fill out much quicker. For us it would definitely mean all squaddies being able to get into the same arena. I can see where Guppy is coming from and it will help alleviate the whole I can't get in and there is no-one in blue whines.
Blue is never really a guaranteed small map though
The only problem I can see is we give up what little action we have been waiting all day for just to help solve an issue that we never really experience. That experience is MMO gameplay.