I would say backcountry, but most of the risks/gnarliness is not apparent to those looking at it from the outside. The conditions/snowpack/avy danger change a lot in the BC. The park is mostly the same. Even if the park crew changes it up, you still know what you are getting into and you have a reasonable idea what speed you need, how to do everything, etc.
In the BC, you are constantly evaluating the weather, snowpack, terrain, and what risks you are taking. There is a whole lot more thinking that goes into it and much of it is before you leave your house in the morning. You have to have self control(deciding to ski a boring sub ridge instead of the huge chute you just spent 4 hours getting to because you aren't confident in the snowpack). You have to have education, experience, and a whole ton of equipment.
I don't know about the comparison because of the danger of avalanches. It seems backcountry wins this argument every time just because of that. You can have a straightforward 38° slope that would be super gnarly and risky to ski on a high danger day, but it would appear as nothing compared to a 100' kicker. It seems apples and oranges. Better question would be park vs sick inbounds lines that are controlled.
As for BC bindings in the park. Just have different pairs. There is no reason for a one ski quiver here. I've used my gaurdians in the park, but I dont even use them in the BC. Just get some dynafits and find a good pair of used touring skis. Keep your park skis for the park.