Without looking at the article you're referring to, are you sure it wasn't about barrel extensions?
The type of barrel nut will be dictated, for the most part, by the design of the rail - HK's barrel nut is designed the way it is so that it can mount the HK rail.
No barrel nut is chrome lined, and I cannot imagine a reason it would be, but if you have a Colt barrel nut, I would be fairly certain that you have the best standard pattern barrel nut currently available.
With so many different rails using so many different barrel nuts, no one has really focused too much on improving the stock barrel nut, though IIRC perhaps Troy or someone released, or considered releasing an "improved barrel nut" designed to be compatible with USGI parts - but I don't recall it gaining much traction.
Most manufacturers are simply going to offer enhanced barrel nuts to go with their enhanced rails, no point in "upgrading" the functional standard part that's bound to get changed out eventually by most people who are hell bent on "enhancing" their rifle anyways.
~Augee