I switched from a KH career to the X10 and IV nearly a year ago and I love it. I love the simplicity of the titration testing. I have recently been experimenting with making my own reagent out of pool acid. it is great that it is very DIY friendly. I would also recommend the salinity probe with the IV mine has been great after using other brands and having horrible results with salinity monitoring I have been extremely happy with the Hydros. I am using the original generation 1 IV. We still have some of these in stock if you are looking to save a little over the new one. I don't know of any changes except for the light shield in the new one.