You could certainly use them together. There are Toon! and Toon! Pro overrides on the Effects tab so that you could assign which one works on which item.

If you're talking about backgrounds like the thing on the Scene's properties, then neither of them actually do anything to the background or backdrop.

Regards,
Eric Winemiller
Digital Carvers Guild
Carrara plug-ins

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins