[MayeulC]

I don't think you actually need reversibility if you don't discard the energy but return it to the power supply?

In other words, "reversibility", but you can actually pool the useless results together, you don't need to separate them later. Or so I read somewhere...

[sudosysgen]

I might be wrong since I've studied this a long time ago, but from what I remember, in order to do that classically, you need to copy the output bits somewhere else before uncomputing your system and recovering the ancilia.

That's technically fine, as long as you have an infinite supply of stably initialized bits onto which to copy your result. Initializing those bits is going to be non-reversible in some way.