i think the 'set back' can also be subjective to how badly the plant needed to be repotted, and the condition of the old medium. timing is everything for some orchids, but if you have waited too long to repot and your plant has lost a lot of roots, the time you are 'set back' with top growth is really the time the plant is growing new roots. you might not notice that going on, but after a short adjustment, i find my plants spend some time growing fresh roots into the new medium. eventually the top catches up, and the plant does much better. after growing those 'rescue phals' in sphagnum moss so well for years, i was scared to repot (they were doing well, so why not wait?) but wanted to build an 'orchid tree' out of treefern pots staked up together. i thought for certain i would lose some orchids, especially since some were old orchids people nearly killed and then gave to me, and some i had accidently sunburned myself... and some in great shape that were in flower, but i bit the bullet. every single orchid is doing well now, and the ones in bad shape are perking up. the ones in bloom did lose a few open flowers, but have since opened more and are still in bloom, months later. i've ordered more treefern pots and will finish the project soon. and i've started a few more outside as this set up seems to work, and provides a nice structure for climbing jungle cactus. but on the other side, if you cannot bring yourself to repotting, get vandas in teak baskets. no repotting ever needed. or you can use the lava rocks etc. that don't really need to be changed much.