i have many trees in smart pots (rootmaker). in my book the more input from roots the stronger output of the top growth. as with potting anything there is a lag phase as plant become accustomed to new home. to continue what ang' said as the roots reach the perimeter of basket the are essentially air pruned/ die at tips, this cause roots to proximally, and ramify.
i'm assuming that your going on the thought process that fine roots mass create ramification, and coarse roots cause coarse growth. If a tree/plant has finer/denser rootmass, it will intake more food, water, oxygen resulting in more growth. I can confirm that top growth is better in smarter/air pot, as compared to similar sized traditional pots. This too is dependent on soil mix, watering and feeding practice.
this style of pots can and do break many of the old potting rules, and pot is not the ground rules. I've yet to match the growth rate of ground grown, yet , but still trying.
check this out.
http://www.superoots.com/airpot_work.htm