I moved some mature sparagras a couple of years ago when i moved house. I dug up as much as i could of the rootball, and kept them in bin liners. I had to chop through finger thick roots to get them out and i thought they would be goners but i am happy to report they are all doing well in their new home.
I would recommend the following:
move them in winter or very early spring,
get as much root out as poss,
plant deeply (about 18" should do it),
dont harvest the first year,
keep all pests off the first year so they are not weakened - particularly the beetle,
manure thoroughly