I take it they are summer raspberries, autumn ones you take down all the canes about now and they fruit on the new growth. I am a continent away, and not so certain about summer ones, but off the cuff I would expect to take out all the older stems in autumn, not winter, here about September, leaving the new ones to fruit. If you take all the new ones as well I am not sure the plant would grow more, maybe try taking a proportion of them. If you left the old ones would they survive and fruit only slightly? I am not sure.
My usual approach to such things is to do some each way, cut a few down to the ground, cut a few of all their old growth and a proportion of the new, and cut a few with nearly all the new cut and only a bit of the old cut. Alternatively I would strike some cuttings before cutting down the plants, just in case I killed them all, or I would follow my usual practice and leave the raspberries for the birds instead of picking them.
