Be aware that there are members of the NTP pool with less-than-honorable intentions and you don't get to pick-and-choose. Yes, they all should provide the time, but they also get your IP address.

For example: unlike the IPv4 space, the IPv6 space is too big too scan, so a number of "researchers" (if you want to call them that) put v6-capable NTP servers in the NTP pool to gather information about active v6 blocks to scan/target.

Do you have any acticles or references about this? That would be great research (pun intended) to find out

Is this one of those extraordinary claims that requires evidence? Or is it generally true that there are homey-pots in many of these services (NTP, mirrors, etc)