Even just from a visual perspective (and it's interesting that you appear to use the normal lore for their background, despite the shift in aesthetics), your interpretation of the Sigmarines just manages to make them so much more evocative and interesting than the usual versions seen (and advertised by GW themselves). By (quite literally) dulling their shine and making them look battle worn, dirty, weary, they become both more grounded and human, while somehow making them more noble and stalwart as well.
I guess what I'm saying is that you've possibly sold me on the concept of Sigmarines. Can't rule out picking some up one day anymore...