I would expect there to be less losses running on 12v, assuming that the CPAP internals are 12v and it's not voltage shifting internally. Smaller voltage shifts tend to be more efficient as does shifting down not up.
The great advantage of being 12v native is if you have an issue with your preferred power supply you have other options (like your LB)
The great advantage of being 12v native is if you have an issue with your preferred power supply you have other options (like your LB)
