|Yes, this was true for Arnold 4, but in Arnold 5 it seems it is like this|
I hope so, otherwise it's not the shader who's energy conservative, it's the user ! Else, if you do all the energy calculation yourself, any shader in C4D is energy conservative.
The shader has to do the math internally so that it's all relative values that sum up to 100% anyway. So if you have 1 in diffuse and 2 in specular, it all comes down behind the curtains to 33,33% and 66,66% = 100%