I'm running a Dell T3600 with a Nvidia Quadro 600 and driver 331.82. I've only been tinkering with it and I don't see a huge difference in the "look" between the two settings. However watching the CPU & GPU meter, it clearly utilizes the GPU more when set to "order independent" rather than "blended". Working with one assembly model with several components set to varying degrees of transparency, the model would spin cleanly with either. With blended, the CPU would be around 30% (15% of that or so is background processes present when not spinning) and the GPU 40%-42%. Switching the setting to order independent left the CPU utilization about the same, but pegged the GPU to 99% every time. I think that would support what Antonius mentioned that it is very dependent on the card. Here is a link to a PTC doc mentioning the support for this setting with Nvidia cards. I take the wording it as it's meant to use the GPU more.
http://creo.ptc.com/2013/08/08/ptc-creo-2-0-order-independent-transparency-support-for-nvidia-gpus/
Erik