They're definitely curious fish. They seem to stare back at me if I'm infront of the tank.I found sp. "Peru" to be a bit more sedentary, though that might've been because the fish was rather large and old. They're also slightly less violent to conspecifics and tankmates, if given ample space IME, but again, that could've been due to my fish being an older LTC adult.
I personally like them more than erythrinus; they just feel slightly different in personality and demeanor.
Good luck with yours!