"koee gaavai raagee naadhee baedhee bahu bhaath kar nehee har har bheejai raam raajae ||
Some sing of the Lord, through musical Ragas and the sound current of the Naad, through the Vedas, and in so many ways. But the Lord, Har, Har, is not pleased by these, O Lord King."
what this means is that u can have all the gyan of raah vedas and all that but rab will not be pleased if naam is missing. sikhi is all about naam jap thats what will count in mahrajis court. so i dont think theres anything wrong in namdhari kirtan as what i know they specially emphasize naamsimeran.
a lot of mainstream sikhs believe the tuk of neel baster phare as someone mentioned before in sou sakhi so it depends on what your views are i would listern to anyone doing kirtan espicially the puraten way of raag vidya how its ment to be done. bonus when the raagi is ful of naam weather naamdhari , nihang akj without naam and love for waheguru were nothing.
ਨਾਨਕ ਭੀਜੈ ਸਾਚੈ ਨਾਇ ॥੨
॥
naanak bheejai sachai nae ||2||
O Nanak, the Lord is won over only by His Name.
http://www.searchgurbani.com/main.php?book...p;ShabadID=1670