The difference between the Taylor K-2005 and K-2006 is the K-2005 uses the DPD test for FC and TC (comparator block and prone to bleach out at high chlorine levels unless you dilute) while the K-2006 uses FAS-DPD for FC and CC (titration test...will not bleach out at high chlorine levels and much more accurate, same as in Ben's kit). The other tests in the kit are the same. As far as the acid and base demand tests...pretty much usless except maybe when acid starting a new plaster pool. The k-2006 has the same functionality of the PS234 except for the acid and base demand tests and includes an OTO test for chlorine and the pH comparator has a wider scale, which can come in useful. Ben's is just a better value for your dollar because he gives enough reagents to do more tests before you need to buy refills (escpecially CYA and the titrants!)