Ever since I purchased my Naniwa Professional (New Chosera) water stone, I've been hooked on it and looking for alternative choices to replace what's left of my Norton 4/8K combo stone. The 4K and lower grits don't last as you can see in the photo below:
Even though these stones provide a really nice and comfortable edge, I simply can't afford to buy the 220, 1K, and 4K stones every year and sooner if I get into honing straight razors for other people. Based on my experience after owning the Norton 4/8K combo stone, only the 8K side and/or stone lasts and I regret trying to save money by going with these Norton combo stones:
Another stone I truly regret buying is the Norton Flattening stone. Do yourself a favor and do not buy it. Your best bet to flatten your water stones is either a 600 or 1,200 grit diamond plate which costs much less than a diamond lapping plate does. The 1,200 grit diamond plate also is an excellent slurry stone. It produces a slurry using the stone itself with no added compounds:
I can't complain about the Norton stones too much because they do produce a nice comfortable edge on straight razors. But in my humble opinion, they're a bit over priced mainly because apart from the 8K, they don't last. So I am looking at various water stones including Naniwa Traditional series which does requires soaking.