Bumping this thread because enforcement starts this Wednesday May 7th and all indicators point to it being a circus at TSA.
But: I will also add that just because Enhanced IDs are legitimate documents, that is no guarantee individual agents will be familiar with it. I have an Enhanced ID and even flying out of NYC airports there have been reports of people being warned that their IDs won't suffice. Lots and lots of anecdotal posts on Reddit from people in other states backing this up as well. TSA agents' training on this seems to be inordinately focused on looking for the star on the card as an indicator of compliance, which isn't the case for many Enhanced IDs (ours in NY just has the flag on it) or for Trusted Traveler cards like Global Entry or NEXUS which are 100% compliant.
We don't fly down until 5/25 but I am still bringing my passport just in case and getting to the airport much earlier than I usually do, despite having an Enhanced ID and a Global Entry card. I hate the idea of flying domestically with my passport but I don't trust these agents.