I''ve always pulle/peeled mine from rock. Worked fine. Otherwise, cutting it low and leaving a gell on the rock only makes for a new growth there again soon. When possible, I used a toothpick and a rubber band to attach frags to rocks. Toothpick through the bottom of the stalk. Rubberband on both ends of the toothpick and around the rock. Ususall, 3 days later, I could remove the pick and rubber band and the xenia was attached.
"Life may not be the party we hoped for but while we are here we might as well dance!"