I've only tried so far with plants that are really tough (for me, anyway), like ficus & bottle tree seedlings & adenium. I do have a baby J Maple in a gallon pot outside. I've pruned the tap root back slightly, and I'll continue root-pruning it so it fits into its gallon container. When it starts developing stronger side roots, I'll prune the tap root back further and put it into a wider, shallower pot. I think if I try to do it by degrees, it will have a chance to adjust its root system accordingly.
