If I have to speculate those who have a strong understanding of the vocal tradition like TNR WHO WAS A GOOD VOCALIST HIMSELF are the ones likely to try Thanam. VKV
the temple nadasvara vidwan at nangallur anjaneyar temple was playing an abhogi alapanai and then.. followed it up with a tanam. with the tavil vidwan accompanying him for the same.
however, by the time the tanam could end, it was time for the evening harathi and hence it was not to be completed.
I think it's difficult: they say it's difficult in flute also, I think nAdaswaram should be even more demanding. (Contrast with the veenai!) Some people tell me flautists sometimes play even pallavis without tAnam.
Thanam singing with kalapramanam is Thruvanandapuram style and I have heard Thiruvenkadu Subramania pillai also playing thanam with tambura sruti and mirudangam.
Thanjavooran