During a Master Gardener class, I watched a speaker demonstrate how water moves poorly from one type of soil to another - regardless of what sorts of soil he used. I have always believed that plants do best if their roots are in contact with the garden soil in which they are to grow with no intervening amendments. I am quite sure most of us do not have bark for soil in our gardens, so I would think it would always be advisable to eliminate as much of the potting medium in which the rose was originally growing possible - without sacrificing roots - before putting it in the ground.
