Any target of high value will be pursued and observed by trained humans with advanced tools. The amount of data collected, I suspect, would be less but more accurate.
A device like this just lowers the bar (really low) on tracking. However, it increases the noise/inaccuracy. If combined with some key logger and other devices, it could provide a very detailed picture of someone's communications and movements. But it would include a lot of noise as well, which would still require a lot of sifting and organizing to make sense of the data (and especially to filter out the noise).
If anything, I think these devices are more a money grab on the "spies" than a significant intrusion on the targets.