I doubt anyone would argue that, but there is a conversion involved in the process of going from SACD/dsd to FLAC/ pcm that can't be completely overlooked. Each of us must weigh the costs of DSD vs the convenience of FLAC. At this point I choose flac's, but I also keep the full ISO's in case my situation changes.
I'm just getting started with ripping my collection. So far, I have kept the iso's as well. No reason really, other than I haven't taken the time to either discard, or archive. It all takes time and space. both, which I"m short on at the moment.