Tina makes a good point, it can vary depending on the situation. A plant transplanted with a soil ball, especially in cooler damper weather/times of year may barely notice being moved even with full foliage. But at the other extreme, if moved bareroot and in hot sunny weather then leaving full foliage is more stressful to the plant, and if the leaves wilt then it is not able to photosynthesize in any case (because the stomata are closed).
I once did an unintentional experiment when some clumps had to be moved hastily in summer. Some were cut back and some were not. They did still have some soil on the roots. The ones that were cut back recovered quickly and bloomed, the ones that were not cut back had their leaves die back and aborted their scapes.
