I agree. I have had better growth putting a whole bunch into a bigger pot than individuals, but the con is that they're harder to handle when grafting. I have also had the 1" per week growth though in individual 4" pots, but not as often as in bigger pots.
Here's what I do though. I grow my mother plant peres in really big pots with several plants in each one. Peres like to stretch their roots out, but their roots don't take up much volume. They are just really far reaching and skinny. So having lots in a single big pot is no issue. Once they get to a good size i cut them and put them in smaller individual pots (or 2-4 per pot sometimes) and let them root. Once they root and grow a few inches I graft onto them.
Then I let those grafts grow for a while. Usually about a year and then I pot them into bigger pots in groups or sometimes individual. Or if they're big enough I will cut the stock down to 2" and root that, then bury it under the soil. This will actually keep the graft going, but the scion will root too. And after a year or two the stock will die and the scion's root system will take over