Have read much over the last few months regarding DNG files and have seen many folk pushing it as being a universal format - you know the sort of thing, convert all raw files to DNG thus making them future proof. Is this really true? Are they universal and if so is the quality of the origunal raw guaranteed
I think this XKCD comic addresses that bit of your post:
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They might have been “universal” if Adobe hadn’t participated in their definition and then as with so many other things, added their own rules on top and diverged. They did the same with metadata after the MWG (Metadata Working Group) defined the “standard”.
whatever “original raw” to DNG conversion happens - it is using some software… software can have bugs and developers can have no clue what information is present in raw files to be transferred… imagine a situation when you did a conversion and the bug resulted, for example, in something that was lost and you deleted the original raws… so don’t be stupid - always make sure to not delete and backup the original raw files the way they were written by camera’s firmware …
even when situation is not about bugs you can end up with an egg on your face if you do not backup and preserve original raw files upon conversion… when Panasonic introduced software optics correction with data written to raw files Adobe was woefully unprepared to support it, so for a while ( till DNG standard got updated accordingly ) tools like Adobe DNG converter were creating linear DNG files only from Panasonic raw files…
so do whatever you want to future proof, just keep the original raws
DNG format was advertised by Adobe to be a kind of “open raw” file format. This was an illusion or a marketing trick. DNG is an extension of TIFF/ED specification, like many other proprietary RAW file formats, but with Adobe products in mind. Moreover, it still contains camera producers “MakerNotes”, which are in proprietary, undocumented format (some parts being reverse-engineered though – see exiftool, dcraw/libraw). It’s simply not in camera makers interest to jointly standarize all RAW format details. It could make implementing new, proprietary ideas impossible. There are patent related issues too. Much is done under NDA.
This is a MUST. Keep backups too 
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