I've whittled down my fig collection from about 15 potted plants to my five favorites that I plan on planting in the ground in my brand new greenhouse. I want to confine the roots so the figs don't overwhelm the other potted treasures I've been gathering for this moment!

I originally thought that I might plant them in 55 gallon barrels with the bottoms cut out. Recently I was looking at some British websites and see that nurseries there recommend that figs be planted in root control bags. The root confinement is supposed to control them and encourage fruiting over rampant vegetative growth.
Here's a link to one company in the US who manufactures them: http://www.treebag.com/smart_pot_in_ground.html Can trees grow in these long term or would this just buy me a couple years of control and then I'd have to dig them up and root prune them anyway? Has anyone used these successfully? What are the pluses and minuses you've experienced?

Thanks in advance. Steve H. SW Wisconsin USA