Just noticed this and felt the need to address this. I cannot speak for scottish hones from experience, I do not own any. From what I've read though, the right one can create a decent shaving edge. Perhaps not as smooth as an escher or coticule, but they will get you close, clean and comfortable.
I do have Welsh slates and Arkansas hones. Slates can slurry, mine do very easily and they cut relatively quickly when slurried up. The edge left behind depends entirely on the slate used. I can match a Norton 8K with my Dragon's Tongue, or I can match an Arkansas stone edge with my Black Welsh slate.
Arkansas stones are a slightly different beast. They're very hard to abrade, and building a slurry made up of Arkansas stone material is simply not worth the effort in my estimation. IF you had one and wanted to use slurry, you'll very much want a softer stone that breaks down more readily. Like a set of Japanese Nagura stones, or a coticule rubbing stone. The edge left by a Vintage Hard, True Hard, Translucent, or Surgical Black (varying names for the same quality stone) is very nice and tough to beat. If their popularity is lacking, it is because they are slow and fairly pricey not because of the edge quality.