Moving Hedychium (Advice Please)

I am planning deeper borders this season and would like to move my beautiful hedychium from the back to the middle, to make way for taller plants at the back. 

I have heard ginger lilies are not huge fans of being moved. Any advice how to minimise shock and/or trauma by digging them up and moving them? http://www.cooltropicalplants.com/Hedychium.html#1st suggests late winter is a good time, is April still okay?

Any hints, tips and words of wisdom welcome.