I can't speak for plug-in pressure cookers but I decided to give our stove top pressure cooker a shot after following the recipe on the bone broth thread. We weren't terribly confident about leaving it simmering overnight either.
It really does take time out of all the hours of simmering and time on the stove top. It's a bit tricky to use at first but the thing is to turn the heat down once it starts hissing before stuff starts sputtering out. If used correctly you'll know when it's all right to remove the lid.
A trick I learnt is to immediately remove it from the stove top at that point, and wrap it it up in blankets or towels, if really must continue the process overnight. For additional insulation and to make sure the blankets stay in place, you can pop the whole thing in a box. The idea is that they retain the heat that would otherwise be lost or that simmering provides.
It really does take time out of all the hours of simmering and time on the stove top. It's a bit tricky to use at first but the thing is to turn the heat down once it starts hissing before stuff starts sputtering out. If used correctly you'll know when it's all right to remove the lid.
A trick I learnt is to immediately remove it from the stove top at that point, and wrap it it up in blankets or towels, if really must continue the process overnight. For additional insulation and to make sure the blankets stay in place, you can pop the whole thing in a box. The idea is that they retain the heat that would otherwise be lost or that simmering provides.