A big plus is that Pickerings roses are virus free.
Not very many virus free rose vendors here in the U.S.
and the Multiflora rootstock is more suited to cold climate growing.
I prefer fall planting bareroots over any other way of planting.
Dormant bareroots planted in the fall have a big head start over
spring - summer potted roses and I've found that Pickering's grafted roses
preform just as well as ownroot roses.
I've been buying roses from them for over 10 years and never been disappointed.