I own the 1K Shapton and have only used the 1K Cho a couple times. The 1K Cho is much more to my preference because it provides tactile feedback that give you useful information about what's happening with the edge. It appears that there's no free lunch, though: In my experience hard and dish-resistant stones like the Shapton Pro 1K and the Sigma Power Hard 1K don't provide much (any?) feel. Stones that do provide good feel (Cho 1K, Bester 1200, Sigma Select II 1000, Sigma Select II 1200) tend to be softer and more dishing-prone. For that matter the diamond pastes that I use on steel plates for really nasty steels don't provide any feedback at all.
My personal favorites mid-grit synthetics are the Bester 1200 and the Sigma 1200, depending on the steel. The only reason I don't list the Cho is because their pricing offends even my sensibilities, and that's really saying something. Magnesia stones do provide a very characteristic "feel" above and beyond the feedback that I referenced above, though, so I understand why people fall in love with those stones.
I'd suggest borrowing one first if you can (I'd be happy to mail you mine if you want) as the 5K has a fairly unique feel even for a Shapton and can be polarizing. See comments earlier in the thread about load-up. I like it, though I like the Sigma Power 6K even more.
Yeah, the Snow White is a nice stone, and quite a bargain by Naniwa's standards. I bought one a while back to see what everybody was so excited about, and it lived up to the hype. Great feel, fast cutting. I also bought it to try to figure out how they get results that good with such a coarse nominal particle size, but I still don't understand that.
I think that including a polisher into a discussion of dishing in mid-grit stones is potentially misleading, because it's fundamentally easier to make a dish-resistant 8K stone than it is to make a dish-resistant 1K one. Consider the following simplified mental model of how waterstones work:
In order to cut quickly a waterstone sheds worn grit. To do so the waterstone must release the surface "layer" of grit in no more time than it takes the steel to dull that layer's exposed cutting points. Because wear happens at the points, it takes (very) roughly the same amount of time for the surface layer's particles to wear out, regardless of grit, so all stones with similar abrasive and target steels will shed layers at about the same rate. The thickness of a layer is proportional to the abrasive particle size and inversely proportional to grit.
If you accept that model, then the obvious conclusion is that a #1000 stone will dish 8X as fast as a #8000 stone, all else being equal. I don't think the reality is quite that "linear", but it's certainly true that coarser stones dish faster than finer ones.