EDIT: searching Google Scholar, it looks like only ~50 papers/books mention reversible computing in the past year, compared to 1000+ for quantum computing.
On a skim it looks like 's argument is that people have been criticizing the overhead of fully reversible circuits, but only 'conditionally reversible' circuits are needed for the power benefits.
 This place is awesome and you should check it out if you're in the area: http://www.livingcomputers.org
How does that square with Landauer's limit?
 Apologies for the lack of reference. I'll try and find it.
("Basically" because there are whole books on the subtleties of physics and information. I haven't mastered them.)
Of course if you can flip it without expending energy then reading it and flipping it if it's 1 necessarily requires the Landauer limit's worth of energy.
It agrees with kT ln 2 when T=0 right?
But OK here's a reference of sorts. Not by Feynman but by Bennet and Landauer. https://www.scientificamerican.com/article/the-fundamental-p...
"there is no minimum amount of energy that must be expended in order to run a Brownian clockwork Turing machine."
Also interesting but I didn't find the exact thing I was looking for:
Simulating Physics with Computers
Richard P. Feynman
Richard Feynman and Computation
Being on mobile and not able to explore in depth, that quote sounds like a variant of Maxwell’s demon. It is correct to say that the Landauer limit is not due to a single physical law that must hold true, but rather a lack of knowledge about the state of the universe and the fact that acquiring that knowledge to do a “free” bitflip requires at least equivalent energy expenditure as that bitflip. TANSTAAFL.