I have never heard of pollarding pear trees. We had old pears that were huge and it would taken a tree surgeon to perform the operation! If you go to some french chateaux, in their potager gardens, they have very old pears and apples kept the exact shape they want, by careful training and pruning. I am not sure how a well grown tree would react to being topped,as I understand pollarding. I would say a good thinning out of old wood and opening the centre of an tree is perfectly OK and might do it good. I 'scalped' 3 really old ballerina apples last pruning and they are fruiting well and not piling on growth as it is so dry....so far so good. Fruit was heavily thinned out.