Currently, we use Planck opacities for T < 1000 K and Rosseland for T > 1000 K. Let's give the user control over this parameter and simply strongly advise them not to change it. It could happen that a situation comes up where they want to change it to, say, 1100 K, or 900 K or something like that. This threshold is relatively arbitrary anyway, so it makes sense to give the user control of it.
Currently, we use Planck opacities for T < 1000 K and Rosseland for T > 1000 K. Let's give the user control over this parameter and simply strongly advise them not to change it. It could happen that a situation comes up where they want to change it to, say, 1100 K, or 900 K or something like that. This threshold is relatively arbitrary anyway, so it makes sense to give the user control of it.