Very interesting article: wish I'd read it before writing mine!
The problem with the current set-up, on both RO4 and RO5, is that any colour scheme will have to be close to grey to avoid colour clashes with major gadgets, such as action buttons. Your scheme is considerably warmer, and very nice. But it would be good to be able to depart radically from the greyness if wanted and keep the desktop looking consistent.
Preferences are obviously very subjective. I do like your file icons very much, and they would be wonderful with an alpha channel. I think I slightly prefer RO4's uniform 'jigsaw' approach to the configure applications, and I'm not sure I'm fully sold on your drive icons. But it's great to have the choice. I presume you're not able to currently distribute your iconset independently of the OS?
I agree about the rounded icons: without antialiasing they look pretty poor. But I think the graduated faces look good when used with restraint.
Finally, I'd noticed the '11Sprites' files in things like NetSurf - I assume these are the high-definition sprites you refer to. How are these currently used? Can RO5 display file icons at double size?