I'm torn when it comes to Koh Gen Do cotton versus CVS sterile rolled cotton.
The Koh Gen Do (KGD) is denser and easier to work with, especially if you are making long thin wicks for applications like the kayfun or Prometey. You can cut the exact size and shape you want, and it all stays together when you install it. However, one reason KGD is the go-to cotton pad for makeup removal (other than the chemical free aspect) is that it does not absorb as readily as standard cotton. This property makes it last longer and function better for facial cleansing and lotion applications. But in vaping, that's not necessarily a good thing. I think I prefer the way standard cotton absorbs - I can get more drops of juice into my wick with CVS cotton - the KGD takes in less, and the rest pools on the deck, which can potentially drown the coil a bit depending on your atty/build.
Also, I do notice a different taste with KGD - I may be more sensitive to flavor nuances than others though, so this may not be an issue for you. It's not a pleasant taste in my opinion... I have not tried boiling it yet. I may do that and report back - perhaps the boiling process will also impact the absorption factor.
I'd have to agree with you on two points: absorption and flavor.
Absorption isn't really an issue in my reo, but the kgd pads definitely hold a little less liquid in my igo-w dripper.
Flavor: definitely imparts and odd taste in the first dozen or so pulls. Where my sterile rolled just tastes kinda muted and cottony, the kgd pads have a distinct "odd" flavor. Not really "chemically", just odd.