I believe if you have a great week priced right it will rent on any of the mentioned sites.
That being said, if you are not competitive and you have a week that no one is demanding then it is not going to rent period.
I advertise on all of the mentioned sites and when one person is looking for something, I get inquiries from the same person on all of these sites.
The rental consumer is as savvy as ever in their quest for the right property at the right price.
I know that most people on TUG shy away from listing a phone number, however, I do believe that the ability to have instant contact with another human being is a very effective tool in getting a rental where there are other units listed. My very fine friend with his wife vacationing over there in this US of A is not going to call me

.
I am speaking of course from the perspective of someone who does this for a living. I will say that my rental business has not been affected by the economy in that people are still renting at an unbelievable rate. My customer who went to St. Martin for the past five years may be driving to Florida this year, but the demand for vacations is extremely high.
JMHO,
Cindy
540-560-2987