Priz, my experience is that Phals are not that sensible to the change to S/H... you can also see in some forum threads and and also in Ray's forum that other people had the same experience. I have moved Phals to S/H even in bloom, without loosing anything
however, if you plant is already stressed, it could be different. Try using some rooting hormones, or just the S/H version of the sphag and bag method: keep it in S/H but cover with a bag (check regularly for fungi!) This method helped a lot two of my plants (Cattleya hybrid and Aerangis rhodostricta)