How many hours has Phase One invested in "Hasselbla" support?
I think that is a very valid point.
All camera raw files contain proprietary information that needs to be worked out. Adobe will want to do that eventually and Phase probably not.
For X1D files there will be a while before good results can be expected. I just did a comparison using H3DII files ( released 2008) converted to DNG and the results were much better than the X1D files. A little darker but nothing major. They should work well in either ACR or DNG process.
ACR and DNG are both Adobe so you would expect similar results, but you would not expect them to be as good as the manufacturers converter in both results and ease of process, and they aren't.