no. there is no considerable battery drain after using windows hello.
windows hello is just the infrared iris scanner, that turns on only when you are unlocking the phone, nothing else. so, there is no batter drain as such.
although it is different in the case of Hey Cortana. They have definitely improved it with software updates, but the battery drain is always gonna be there. the phone itself mentions that battery will drain more quickly when hey Cortana is on. That's simply because the sensors have to be active all the time, processing every sound input it gets. so it is only natural the battery will drain more quickly.
for me, on my 950xl, it worked okay. they battery drained considerably faster when it was on. so I prefer keeping Hey Cortana off. But iris scanner Windows Hello has been working like a charm.