Is the PDF experience better with a text layer?

First off, I've yet to install KOReader so these are pre-install questions...

KOReader has an OCR function, which is awesome, but how accurate do you find it? I suspect it depends on the image quality? Also, with a Kobo Aura (original), will the OCR process chew through the CPU causing battery drain and sluggish behaviour?

Before installing KOReader, I've been ingesting PDF's into Calibre, but only those with a text layer. I'm looking for as close to an e-pub experience as possible, so my assumption is Reflow works best with text layer as opposed to OCR'd image layer.

Is this assumption anywhere close to accurate? :chinscratch:

Thanks!