As a diehard Kishore fan it is actually very painful to hear anyone trying his songs, including Kumar Sanu (who came the closest in my opinion).
The idea is to forget Kishore and just enjoy the singing as recreations.
In that the girls fare better because they sound different and you are not comparing. I actually enjoyed their singing more through the 2 episodes.
Some singers are going off tune, it would be ethical to at least not give them MBD's if you do not want to correct them publicly for business reasons.