Hi Jill,
I'm a personal trainer and RYT (200+ Yoga Alliance). I would wonder about your shoulder only to the extent to the point of how much you are doing in the circuit training and what type of power yoga video you are doing. I wouldn't have a problem with it, but I don't have any "issues" with my shoulders. In fact, when I do yoga, I actually add 2lb. wrist weights because I've done so much yoga that I don't feel it in my shoulders any more.
To be extra careful, can you exchange out the shoulder work in the circuit workout and then use the power yoga session as a true shoulder workout?
Just a thought. Good luck!