Talented freelancers do themselves a disservice by using either of these "services". The only reason for a talented freelancer to use them is out of a desperate need for even abysmal compensation. This merger will likely make things worse for them (freelancers), not better.
Yes, I know there are some freelancers working on these sites who earn a "decent" living. They're anomalies. The vast majority of workers earn really horrible wages. The well paid oDesk or Elance freelancer is as common as a rags-to-riches startup billionaire in the software industry as a whole.