I've passed through security without valid ID once or twice, and it amounted to the same level of checking that you get when your bag gets pulled out of the x-ray for something that looks off. Full pat-down, explosive-residue swab, and they took a look at the contents of my wallet (assorted credit, library cards and corporate ID). It wasn't a serious delay.
Your milage may vary though, if things are already busy then you might be left waiting for a while. Best to err on the side of earlier.
I wouldn't recommend it at all to people who are regularly profiled and hassled by TSA even with ID, of course...
You can also get the check mentioned in the article where they call somewhere and try to identify you with silly questions culled from public and private databases, not unlike some id checks you get from online banks. This can take forever as you're literally playing telephone.
Your milage may vary though, if things are already busy then you might be left waiting for a while. Best to err on the side of earlier.
I wouldn't recommend it at all to people who are regularly profiled and hassled by TSA even with ID, of course...