Teasing out returns on R&D would be difficult. Companies that maintain R&D teams (Microsoft, Yahoo, AT&T, Google, Intel, etc.) tend to be industry leaders, which complicates the relationship between research and income. Further, research projects have varying timelines and levels of dedication -- you can work on a project full-time for weeks, only to table it for immediate needs -- so the NPV calculation would be difficult.

I bet R&D departments benefit from economies of scale -- 5 PhDs can likely produce much more than one PhD at 5 companies, and a solid team attracts top talent -- which means the aforementioned big shots are the likeliest to produce meaningful research. Still, I would give a lot to work at a something like a "research startup."