Well, I don't have much of a problem with sentient powers, especially if they're a mask for someone or something else.
In a way, they're already here in corwin's saga. The Pattern and Dworkin are one and the same (and dworkin is sentient, right?), and we have the unicorn, who is kinda an avatar of the pattern, and which is sentient enough.
So if you have a problem with Pattern vs logrus, maybe think dworkin vs suhuy. Or scrap the war althogether.
Maybe the powers, per se, aren't sentient, but, for exemple, Dworkin is so close to the pattern that it reacts to his every wish, even unconscious ones, making the distinction quite hard to make.
The Spikards are, IMO, at least as problematic. Making them drug-like (addictive, and fatal in the end) is a very first step.