Yes, further reading shows frequent guard rotation causes:
- Increased risk of correlation attacks.
- Greater chance of hitting Internet infrastructure points controlled by advanced adversaries (IXP, ASes etc).
- Greater chance the set of guards in use get fingerprinted, then, adversaries who are able to enumerate guards can link that to specific points in the network based on damn mathematics (not for everything, all the time though).
That said, at least it’s not Tails, where they don’t have persistent guards, meaning new ones all the time, making someone using it at home for example, extremely trackable (damn mathematics again).
Yes, there are a couple of Trac tickets at least talking about it i.e. sustained attacks and limited countermeasures currently available. It will become more sustained unless they change something in the design to afford more protection.