re: "Guaranteed departures with even 1 person"

I would like to have some confirmation (or clarification) regarding the statement above. I am seriously considering joining a small group tour through your company when my friend and I plan to visit China this October 2011. Meeting other travelers in a small group setting will be part of the fun and experience; but my fear when it comes to small group tours has always been the possibility of cancellations by the touring company itself for not being able to attract enough people to join the group. I would like another reassurance from your company that even if my friend and I are the only ones to sign up for the tour by the designated departure time/date, that our trip would still be fulfilled without any glitches. Is there a catch to this "guarantee"?