I would say it is about 95% with a good calibration. I have found that electrostatic headphones like Stax are needed to get the best illusion. A Stax set is what Smyth recommends. Headphones can't replicate sound waves hitting your body of course, but the Realiser does allow use of subs and tactile transducers to help make up for that (i have never needed that).
If i still had a dedicated room, i wouldn't abandon speakers. But unless i had a really nice setup, i would likely use the Realiser more (the Acoustic Zen Maestros i measured are almost 50K) and definitely for surround as i can now properly listen to all the multichannel discs i have collected. I tried years ago to have a quality surround setup but gave up to focus on two channel.
All that said, the Realiser to me is the best purchase i have ever made in this hobby not only because it is technically amazing but also because it does away with the need to deal with the room, treatments, speakers, components, etc. which has proven difficult with kids and moving. Plus i can capture the output digitally and play back on my iPhone using IEMs to walk around with speakers in front of me (and around because surround is captured as two channel file).