Is the ratio Brain Mass/Total Mass still considered a valid indicator of intelligence?
I don't know about brain mass to body size, but ratio of neocortex to brain volume is correlated with primate evolution (Figure 3, here). If you subscribe to the view that humans and more closely related primates are more intelligent than more distantly related primates, then that is an important correlate.
I think the issue with this question is that we're still having trouble defining intelligence.