It's an almost 5 year old article.

Never heard of it before, it was so good, we all would have likely heard more about it.

My understanding is the tip vortex is based mostly on wingloading, the higher the loading the worse the vortex is (everything else remaining the same).
Some airfoils & aspect ratio's are worse than others in terms of vortex with a similar wingloading. And yes, speed has an effect as well.

I would like to see the actual tests performed between a "plain tip", winglet and this device.