OK, thanks for the additional info, that helps to understand your situation a little better.
Yes, the XMP files should be stored right along with the originals. You could double check to be sure though! 🙂
So, in my opinion there’s no need to convert to DNG until you switch to using PS Elements for editing.
You would need to test whether a DNG file that you edited in Lightroom will show those edits in PS 13… If they do, then you might want to keep converting to DNG before editing in LR, that way your edits will be preserved later if/when you switch away from LR in the future.
If LR edits aren’t reflected in PS 13, then there’s no need to keep converting to DNG.