When you split a bamboo it takes energy to recover. When choosing a bamboo go for roots over stems every time. Large culms look attractive, though if you can't be sure they were made after the bamboo was potted on then go for the 'Weakling' that has roots splitting the pot apart. Bamboos can't get potbound by definition unlike shrubs etc. Always choose roots over shoots every time as that is where the potentials is at.
Some species like Chusquea and can be very difficult and labour intensive to split, even seemingly 'easy' running species like Chimonobambusa are a struggle due to the sparse root systems on the runners. Failure rates can be high which adds to costs...