I believe that being a Nicroburst in Mistborn Era 3 would be better then any other type of metalborn. Why? Because of unsealed metalminds. The Nicroburst in question would be able to burn any unsealed nicrosil metalmind and gain whatever power was stored within it, allowing them to collect Allomantic and Feruchemal powers. And, once they got Feruchemal nicrosil, they could store, say, Allomantic steel for a time, compound it, and become much more powerful then before. The Bands of Mourning allowed you to become a Mistborn and Full Feruchemist at the same time, but only as long as you were tapping them. This, however, could do the same thing, but without that limitation.
You've found this totally pointless secret! Yay!