I haven't done KTTK solo, but I have done Backstage Magic (twice), UFW, and Hidden Treasures (full day) solo. I love doing tours solo, you often will be able to strike up personal conversations with the guide and get additional info. Often, particularly on the longer tours, I was able to strike up conversations with other tour participants. The only thing I was slightly nervous about during the tours was lunch but I have always found the other tour participants and the guide to be more thn welcoming and make you feel comfortable (Although my Hidden Treasures Guide did try to force me to dance with the Moroccan belly dancer, saying I was the only one who couldn't get into trouble. LOL!)