Keep the original raw format unless LR can't read it - you gain nothing converting to dng, and might be losing something in the conversion.
Personally unless you have a great need , such as LR not recognising your RAW files I can't see the point.
This may be of use
Difference between DNG and RAW File Formats: Pros and Cons - Teknologya
One of the most frequent and important questions that an aspiring photographer can ask is which of the format to use, namely: DNG or RAW? These two formats have ... Read moreteknologya.com
It seems the files from my Z7 are converted automatically to dng. files in LRc?