Is the BDI2 still a valid assessment tool now the BDI2 NU has been released?
The BDI2 NU is the same test and the same materials as the BDI2. The only difference between the two, is that the NU version, the scores are compared with updated norms.
If you already own a BDI2 kit, then you only need to buy the NU Examiner's manual to upgrade to the BDI2 NU. If you are buying this for the first time, then you should purchase the NU kit, which comes with the new manual.