I think we have to take the next step in discussing Raja's inputs from a historical perspective.
So far we have covered nostalgia, style and lyrics sufficiently.
I thought one thing we have not covered and which can enrich us is the evolution of 'Technique'.
By Technique I mean the things that we associate with Raaja like the vocal counterpoints, orchestral counterpoints, preludes, interludes, instrumentation,fusion, choral portions, scale transitions and so on. All of them need expert participation and we can probably coagulate all the blog links of experts like Vicky and Ravi Natarajan in one place for this purpose.
From my personal listening experience, Over the decades whatever has changed, one thing remains steadily fixed as far as Raaja is concerned - that is the 'Fidelity' of context. By that I mean the relevance the musical piece has to the drama on screen is paramount with even melody coming in secondary - a reason why he was able to create 'noise' and put it in some of his songs like the 'Thenampettai super market' which got on to my nerves everytime I heard 'En Kanmani' or the unnerving gruffness that underlines 'Ennada Paandi'.