We had no curse squad until about T13+. Assassins we had, though. DS picked up RoW and RoC, though. Impersonation was in the ocean.
As for how to counter, the FP need to come up with 2 of the agent rings.
I think not letting SG start with the Ring of Impersonation is a game imbalance for 2950. DS start with about 8 agent items and the FP get one +10 agent and a few stealth items.