Yes. DxO Optics Pro
does recognise NEF files... but from what I recalled (I have no access to their forums now as it's only for registered members), they
do not read NEF files once they have been saved using NX2, even if you have made no adjustments. If anyone can confirm that NEF files saved via NX2 are recognised (fully) when opened using DxO -- I'll be a happy man
I don't get your message which regard to the second paragraph. I thought all adjustments made in RAW using NX2 are non-destructive and are easily, or to be more specific, completely reversible? Unless you are talking about the 'batch feature' of NX2 of which it's a no-go for me (I don't use it).
In any case, this DxO promotion is very attractive... I like the fact that they have 'very specific lens correction modules'. I am not sure if they have the 'keystone correction module though' -- currently, I have Adobe PE5 to take care of that.