Well , jumping from DMT stones to waterstones is problematic. They leave scratches much deeper than their implied "grit". This makes diamond (atomas and other diamond plates included) scratch removal difficult with the 1k shapton. And can leave problems that are difficult to troubleshoot later one , particulairly at the 5k level. I would definitely be eyeballing a 220 or 320 fwiw.
The 1500 sets you up a little better for the 5k imo , its quite a bit harder than the 1k , and softer than the 2k , its an underrated stone. I never use to use it much but im using it more and more and actually skipping the 2k.
Well I haven't wore any out yet , possibly because I have all three , and I am only using EP sized pieces.
Ive least experience with the 120 , I find it fast but messy , seems to wear fairly quickly. Only used it a handful of times. Id be interested to see how it holds up under the hands of Jason.
The 220 is quickly becoming my favorite , hard yet still fast , needs less flattening than the 320 or 120 stones. I find myself reaching for this stone most often.
The 320 is the softest yet surprisingly fast , the slowest of the 3 by comparison. It also requires the most flattening , on the EP I flatten before making my final couple passes so the edge is true for the 1k , not an issue freehanding where you have some leeway built in. I used to use this stone the most before I got more experience with the 220.
I have the full lineup of pro stones , but everytime I pick them up I learn something new , ultimately im sure you will be happy whichever way you go.
Jason I don't have a lot to compare to right now , I have some Nubatamas coming and will be picking up the Choseras from Ken at some point in the future. Obviously all three of them destroy the stock EP stuff in terms of performance. Even wear rates are much better.