I'm so glad this feature will finally be implemented! Will save many headaches.
In its current form, can the coronaslicer only cap in one colour? For the icing on the cake, is there a way to set up multiple cap colours?
Currently when using the slice modifier, I simply create a 2 mat multi-subobject material to give the sliced part of an object a different colour. (Slice modifier + cap typically assigns mat id 2). This allows you to differentiate between sliced, nested objects and have the slice plane as an instanced modifier.
Attached is a crude example