FS-Mark is certainly much faster on the USB 3.0 Flash Voyager over its USB 2.0 predecessor, which would warrant the couple extra dollars for the USB 3.0 model.
The Dbench results also weigh in favor of the USB 3.0 flash drive.
For PostMark there's a slight lead to the USB 2.0 Flash Voyager, but the results are close and this may come down to shortcomings of this mail server benchmark, albeit not a real-world workload for a USB flash drive.
Overall, on Ubuntu Linux there are noticeable benefits to using a USB 3.0 flash drive over a USB 2.0 drive of the same brand, product series, and capacity. In terms of the Corsair Flash Voyager products specifically, the USB 3.0 16GB Flash Voyager is worth the couple extra dollars it costs more than the USB 2.0 model. The only other downside of the USB 3.0 drive is that it's backed by only a five-year warranty compared to ten years with the USB 2.0 Flash Voyager, but if a USB flash drive lasts only five years and costs just over $20 USD, it's still a rather reasonable deal.