I'd suggest you also look at the Corozal Town area. Cheap, safe, friendly, convenient to Mexico. Very few expats in Orange Walk Town area, although there are a few in rural areas. Progresso (assuming you mean the Progesso Lagoon area) is pretty remote but beautiful.
Most of the people who have applied and have been accepted under the Qualified Retired Persons Program seem to be quite satisfied. There are some disadvantages to it, and some people prefer going with the regular residency program.
Bill Wildman (in Consejo Shores) is the quality real estate person in Northern Belize. He's been in Belize for 30 some years, has surveyed a lot of the country and knows it well. Quite a difference from some of the "180-day wonders," folks in resort areas who become instant Belize real estate agents.
M y new book on living/retiring/investing in Belize will be out from Avalon this summer. I hope it will be useful to those who are thinking of Belize but who want a candid evaluation of the situation.
Belize First Magazine http://www.turq.com/belizefirst/