Hello! I noticed the same issue last night at my first band rehearsal with this unit. Would drop out occasionally (randomly - maybe 4 or so times during a 3 hour rehearsal). The drop out would only happen for a quick half a second or so - very noticeable.
however - I DID NOT plug the wireless into the Guitar IN jack - for some reason I though it only needed to be in the cradle. Will do next time and see if I have any probs.