Whites #1 and #2 are very similar, but #1 has more carbon. #1 is stronger, but not as tough as #2. Everything else being equal, white #1 will take and hold a slightly better edge than white #2, but it is more chip prone. White #2 is less expensive than #1, and is a better practical performer -- especially for a gyuto which gets a lot of impact. You could probably make an argument that #1 is better for a chisel edged knife which does nothing but slice fish, but I wouldn't know.
Probably the most important phrase in the preceding paragraph is "everything else being equal." For your purpose, everything else is NOT equal. The Fujiyama knives are not equal to the other Konosukes in that they are not lasers. They are thicker and heavier, and although they're also stiffer I have no interest for myself. Furthermore, it's highly unlikely that anyone other than a very skilled and painstaking sharpener would be able to exploit the minor differences in edge properties between White #1 and White #2. Even if I could, I'm pretty sure the difference in use would be meaningless.
ZDP189 is a metallurgical powder alloy. It has excellent wear and sharpening characteristics. An internet acquaintance of mine, a knife and sharpening junkie of epic proportions, and something of an EP pioneer, has one and loves it. I don't think it's worth the money unless you're as crazy as he is. The "improvements" in the alloy relative to White #2 and HD aren't going to help you cut onions any better. If you want to fool around with an exotic powder, you might think about the Richmond Ultimatum.
As to the Ultimatum in any alloy, worth a thought if you're interested in a KS but can't swallow paying $300+ for a kitchen knife; and/or are interested in "interesting," American manufacturers. On the other hand, not only is a Masamoto a Masamoto, but the KS is the quintessential western Masamoto. I'd have one or the other in my kit, but simply can't make up my mind for all of the above reasons. Since I already have a 10" K-Sab chef's, a 270mm Konosuke KD gyuto, and a 300mm Konouske HD suji which I sometimes use as for chopping, I'm in no hurry to get another chef's.
The difference between the original and "new" Konosuke shape is that the original has some belly and rocker, and the new knife is significantly flatter. The old knife has a more French style and suits a "glide" action, while the new one is more suited to push cutting. The old shape suits my action perfectly. FWIW, my HD gyuto is the knife I most often use for general prep. I don't know what the difference is between HD and HD2; you should call Mark at CKtG and ask.
The Masamoto KS is not quite as thin as a Konosuke White #2, but almost. It's significantly thinner than the Fujiyama. The Masamoto KS, Konosuke White #2 and Konosuke HD are three of the five or six best chef's knives I've ever used. If I had to choose one among the three to use as my only chef's knife it would be the Konosuke HD.
The ten inch range (240mm, 245mm, 10" and 270mm) is a more efficient and better length for home users and pros than 8" (210mm). The exception is people who work in a very tight space or on a very small board. 8" knives are definitely easier to control if you don't have a good grip. Otherwise, they are not. Some people, usually women, tend to think that shorter knives are better for people with small hands, and/or are otherwise "petite." Not true, it's the grip. It's better to spend a few days improving your grip than spend the rest of your life using a knife that's all tip, requires lifting the handle to heaven to chop an onion, dulls quicker, and has all the other short-knife flaws. In my opinion.
No matter how good the rod hone, steeling is not particularlly profitable for very thin, very hard knives, nor for knives with highly asymmetrical edges. Thin, hard knives tend to chip. As a rule, the harder the chippier. Thin knives don't out of true very easily, and when they do it's more efficient to true them with a touch up on a fine stone or strop than on a rod. In spite of knowing that, I occasionally use a hard, ultra-fine (HA borosilicate) rod on my Konos because it's easy to get to. But it doesn't work the same magic it does on a Sabatier or a Forschner.
Regarding the HA borosilicate rod in particular. It's an excellent rod, best as the ultra-fine in a two rod system. It's also very expensive. I do use two rods and use HA borosilicate chasing burrs and when the knives are still fresh enough off the stones that they retain some polish. If your knife kit includes knives which need steeling, and you're only going to get one rod, get an Idahone fine ceramic. Not only is it more versatile it's considerably cheaper. You can add the HA later if you feel the need.
BDL