From my own personal experience in cloning(it's been 16 yrs now ) the top appical shoot is the worst part of the plant to clone. In my experience they always take longer, and that's if they root. Alot of the time they end up dying. In my experience side shoots and even some lower ones clone the best especially, if it's only as big around as the inside of a bic pen(the part that holds the ink).It will be very interesting to see if the tops will show roots faster than a regular branch cutting. I belive that at this stage all the appical hormones from the tops will have some influence on the clones growth.