I'm sure some will disagree, but both agencies are for the most part reliable, in that unless the particular lady cancels her tour (which does happen from time to time), they'll deliver as promised.

And not to speak for the ladies, but some prefer booking direct, some don't.  The agencies offer them some advantages, such as sharing some of the expenses, and more importantly, doing the screening and verification.  Those who are business and computer savvy will often handle their own booking, while those who don't have a computer or wouldn't know one from a toaster oven need the agencies to handle the process for them.