Ilaiyaraaja’s liking for this raga (Hamsadhwani) is evident from the way he has handled ‘Sri Ranga Ranga’ from Mahanadhi. The last lines in the charanams culminate with a phrase that goes like ‘R,R N,P NN P,GPP…’, and such swara patterns are very sound and highly creative.
The one thing we should be very careful in analyzing Raaja sir's songs is sweeping carte blanche - calling this song is this raga etc. definitively. Yes, there are songs he has composed in '100%' Gowlai, Kaanada, Rasikapriya etc.
Raaja sir's songs demand active listening if we are to go into raga guessing mode. E.g. Sri Ranga Ranganathanin starts off in Mohanam (after the initial chanting ends). First interlude is in Mohanam. Hamsadhwani only begins from the first charanam line 'kollidam neer meedhu nartanam aadum'.
The quoted extract from the Hindu article on Hamsadhwani seems to suggest that the song is in the said raga. However mentioning the appearance of Mohanam here would be more accurate and helpful for potentially discerning rasikas to appreciate how these two ragas (which will almost be never sung back to back in a Carnatic concert) have been so well handled without confusing the general listener but yet the N3 leaves the impression that the song is tuned in Hamsadhwani alone - to even some of the discerning rasikas, till one looks into it more keenly.