http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=106

Grasa,

I have used a similar method with bamboo. For those we used 55 barrels with wholes drilled in the bottom third of the pot and them rubble rock placed up to the drilled area. We then followed with the soil mix for the bamboo and then planted the roots. Every few years we dig them out and replace the soil and divide the plants.  

My practical experience tells me differently!
All my plants are still with green healthy leaves, after ripening the crop, just beginning to show some signs of fall. However those plants with restricted roots, not pruned for the past three or four years, did miserably with fruit size and ripening; small fruits, less ripening and these plants started showing yellow leaves in mid-September and the first to drop the leaves.
There must be a limit to root restriction for the benefit mentioned in the header..