Obviously we think Smart Pots are the best, but don't take our word for it. Here are some studies and write-ups for your enjoyment.
Oregon State University study about Root Pruning in Fabric
Texas A&M study about the
advantages of Smart Pots vs.
University of New Hampshire
article about the winter survival of
plants in fabric containers.
Smart Pots in the Wall Street Journal
Smart Pots write-up in National Gardeners Association