I used them for a bit, a long long time ago. They were really much more like a squat than a deadlift, since the torso's near vertical leaving the legs as the prime mover.
Training while your torso is twisted may or may not have value depending on your goals. At that point in time, I was interested in being strong from a bunch of different angles, so I was also doing stuff like Steinborn squats (didn't have a squat rack yet) and one armed presses. In the context of powerlifting, I doubt there's much benefit; if you were training for some variant of wrestling/bjj/judo, it's probably useful. Even so, regular squats and deadlifts + heavy sandbag work might make more sense.
If your goal is to get better at powerlifting, I probably wouldn't spend any time on them. If your goal is just to get stronger, they might be worth including in your rotation for a bit to see how they agree with you.