It looks as if I'm going to get into this thread a bit more than I originally intended.
As I mentioned in the other thread, I am no expert on the santoku, but I did buy one earlier and found that I did not like it. The specific knife I bought was a Henckels Zwilling Five Star, which is now discontinued, but is the same blade as the Four Star, except that the handle was an "ergo" handle.
At one point, I pulled out my handy-dandy-taking-a-measurement-is-everything best dial gauge caliper, which measures down directly to 1/1000 of an inch. I trained it both on the Henckels santoku and a new Tojiro DP gyuto. The Henckels santoku was a great deal thicker - by far!
Which brings up the first of several important things to consider - edge sharpenings being the same, a thinner blade is going to be easier to cut through something than a thicker blade. Thicker blades will have more wedging than thinner blades.
Second, generally, a forged blade will be thicker than either a stamped blade or a machined blade.
Third, for different knives using the same type of steel, any difference in the edge taking and keeping ability will be strictly determined by the heat treatment (annealing, quenching and tempering) during the manufacturing process. Same steel type + same steel heat treatment = the same edge quality. Forged vs. stamped vs. machined makes no difference in edge quality after heat treatment, when starting from the same type of steel. But heat treatment specs are unique to each knife manufacturer and are usually trade secrets. That's where a real difference comes in between different knife manufacturers.
European knife makers usually make several lines of knives, with their prestige lines using better steels, as well as better fit and finish. For most of the German knife makers, Including Wusthof, Messermeister and Victorinox/Forschner, the steel used in the better knives is X50CrMoV15. Victorinox in fact uses it for all of their knives. Henckels Zwilling uses a different steel. X50CrMoV15 (also known as Krupp 4116 steel, and also designated with the technical numerical classification of 1.4116) is a moderate quality steel, good for holding a moderate edge for a moderate amount of time, but really good for resisting chipping. Knives made with 4116 steel generally tend to be made a bit thicker than comparable Japanese knives.
Victorinox makes knives in three different series. Their best known are stamped steel knives in fibrox (molded) handles. They also make a line using the same stamped steel blades, but with rosewood handles and they make a forged knife blade series. There is no performance difference between the two lines using the stamped blades.
If you are really interested in Victorinox, to minimize wedging issues, I would suggest you look at the Victorinox rosewood handled stamped blade santoku, which costs $42.24 on Amazon. The steel is 4116, and the blade will be thinner than the forged version, which will make a considerable difference compared to the forged version (which will come with better fit and finish, though that will not affect the fact that the forged blade will be thicker and will take more effort to cut through the same foods).
The Henckels knives you refer to are at least Zwillings ("Twins"). That is the better brand, mostly made in Germany. Thank goodness they are not Henckels Internationals (single stick figure). The Internationals are the big volume mass market knives, ranging much further downwards in quality compared to any of the Zwilling knives.
The next step up will be a quality Japanese knife. These will be much closer in price to your upper limit. Japanese knives are made with steel which is optimized for hardness, but that also makes them a bit more brittle. The usual recommendation is to not use Japanese knives around either frozen foods or around bone - or expect chipping!
Look on such sites as Chef Knives To Go, Korin Knives, the Epicurean Edge and Japanese Knife Imports. You should be able to get a good selection of quality Japanese santokus and get good measurement information about the knives (CKTG is especially good about posting blade thickness info).
For your price range, I would tend to discount or ignore knives with "Damascus" blades. You need a knife or knives which concentrate their quality towards being working tools, rather than "Drawer Queens" (knives which are so fancy you are unwilling to use them for fear they might get damaged - and are referred to as "Drawer Queens" because they never get taken out of the drawer). Damascus blades end up being "Drawer Queens"
Look at hardness ratings - you preferably would want a knife with a Rockwell Hardness of at least 58 - of the European knives, only the newer Wusthof 4116 steel knives and maybe the Messermeisters are at that rating. Victorinox knives are heat treated to about 56. Almost all of the quality Japanese knives meet or exceed that hardness rating.
As I said in an earlier posting, I wasn't really wanting to make recommendations about specific knives (I do so here about the Victorinox Rosewood santoku because of its low price, but temper it because of its hardness rating), but general information is a different issue. What I list above is mostly general information about knives.