When you say "hack them back", are you going to cut all the canes to the ground? If you do you will not get a harvest next year. You can remove all the floricanes (last years growth, this years fruiting canes) now if you wish, but I would recommend trying to salvage the primocanes (this years growth, next years fruit). Cutting back all of the primocanes may weaken the plant too much as it will spend a ton of energy trying to replace all of the lost canes by growing new ones. I would try to treat the aphids with a product labeled for them first. See if that is effective before taking more drastic action.