Well, you learn something new every day! I still reckon brass isn't a great choice of material, but looked up the Coefficient of Linear Thermal Expansion for brass versus Austenetic Stainless Steels and it turns out they're very similar, 18-19 versus 16-18 respectively. So arguably, brass has better casting and machining properties given it's lower hardness. @Korbz: May I ask what razor you have pictured there? A Rockwell 6S arrive on Friday and I used it on R2 for the first shave yesterday... very interesting outcomes. I'm comparing it to the most effective configuration of the AS-D2 I've tried so far which is using a Feather blade with a single 0.1mm shim under it. Firstly, it's worth noting that the 'aggressiveness' and 'effectiveness'of the R2 plate compares pretty well to the Feather with a shim. The major difference is tolerance for errors and pressure. The Feather AS-D2 is reasonably forgiving, but the 6S allows me to move around much faster without concern for nicks or irritation. You can see from the image the very different head designs of the two. The Feather is very similar to the old tech I have, where the 6S more closely resembles several of the newer style designs with a larger relief behind the blade. In the 6s image I've highlighted the 'flat' pre-edge and post-edge reliefs, and also the 'effective' reliefs when you consider that the 6S has a slight angle on the wide bar. The presented angle of the Feather is slightly shallower, but I think the relief behind the blade on the 6S, rather than in front of the blade like the Feather, goes a long way to ensuring addition pressure doesn't make the presented angle steeper. On the contrary, I think added pressure on the 6S would tend to decrease the presented angle where on the Feather it wold increase the presented angle due to the way the skin would expand into the reliefs. Another interesting note is the support point for the blades on each. The Feather has a very dead acoustic presence, while the 6S really sings which I believe can be attributed to the support point. The 6S has it's support way back behind the edge of the cap, where the Feather has it's support very close to the edge almost directly below the edge of the cap. If you look carefully you can see where the blade and the shim are being pinched under the cap. So, it appears to the me that the Feather is a fairly traditional design with a well supported edge, but lots of pre-edge relief. While the 6S appears to be a more modern design with a fatter bar and very narrow pre-edge relief which may be guiding the skin into the edge with less concern for pressure. For the sake of reducing the number of variables I've use the same blade, same prep and same number/direction of passes. Weight is similar and I think static presented blade angle differences are negligible. Any thoughts?