I have an EAI Superstar on a 7710 hub and a regular EAI on a Formula/Ambrosio, both are fine, but Phil Wood themselves don't recommend using EAI (and some other cogs) on their own hubs.
If you've bought Phil Wood hubs, spend the money on the Phil cog & lockring. Otherwise you should be ok.
I have an EAI Superstar on a 7710 hub and a regular EAI on a Formula/Ambrosio, both are fine, but Phil Wood themselves don't recommend using EAI (and some other cogs) on their own hubs.
If you've bought Phil Wood hubs, spend the money on the Phil cog & lockring. Otherwise you should be ok.