Mixing bamboo, it's a common question as whether it's a good idea to mix bamboo and in general it's not.
In essence what's not to like, creating interest using alternating species offer interesting colour variations, or blocks of colour to break up a long continuous screen. But over time, unless each bamboo species is planted within a root barrier, the eventual spread will see these colours merge and dilute each other, and look fairly untidy, not the desired outcome.
Also, there is the issue of competition, different species will grow with different vigour and this will create an unhealthy competition for light, water and nutrients. Differing growing habits will also generally result in a fairly uneven, non-uniformed screen.
Call me boring, but I do like to see a screen of bamboo nicely uniformed with a consistent and tidy form with each plant withing working together rather than competing against it's neighbour. Of course this has a lot to do with personal preference, but if mixing bamboo is for you be sure to contain each variety for best results.