Someone else on this forum did that and he said that the coralline from the fiji rock took over those on the lalo. Lalo has yellow, red and green coralline instead of PURPLE on the fiji rock!! (which IMO is overdone) That's why I think base rock would be the best if you are going to spend the money on the lalo because the lalo coralline will seed the base rock.
But to answer your question, yes you can mix all types of rock. Each has their own unique shapes and colors so get lots of pictures!!