I looked at the new 4000D mini baitrunner and again, I think the spool diameter is too small plus I think the green finish looks like plastic and will scratch easily.
Not quite sure what you've looked at but the 4000D doesn't have a green finish.
Perhaps you saw the XTFA?
I have both XTFAs and Ds (plus GTEcs with a similar finish). The glossy finish is applied over the top of XT-7 that Shimano have used for reel bodies for years.
In my experience, the shiny finish actually shows any handling marks less than the matt graphite like finish of the older reels such as the 5010 GTMs.
However, it might be another story if you are so rough as the chip the finish. I can't say for sure as I've never been that rough, even with 15 year (plus) old Stradics with their white finish.
---------- Post added at 15:43 ---------- Previous post was at 15:41 ----------
By the way, has anyone actually managed to track down a full paper copy of the new 2012 Shimano catalogue. I'm assured that they exist but can't find one for love nor money.