this is a thread I am interested in too. (flying to Belize in 10 days). I really dont want to spend the extra 1,5 hours if the price difference is not going to be significant - especially if the taxis started to ask for 50 bucks to take you to the ferry.
if we share taxi 5 way, one way cost will be $10+$20/head to san pedro from the airport. tropic air charges $60 one way, right? ... hmmm... decisions, decisions... It would be great if TropicAir (or Maya air) did group discounts (there will be 7 of us), or promotions.