Some excellent observations.
…the flavor of tobaccos with cotton [ is ] better.
Yep, cotton does
stain with some flavoring pigments. Like certain juices in a pan. These mature
while wet as vaping progresses adding distinctiveness. Dry the wick, overheat it, and likewise these elements can taste as bad as any charred leftover when re-heated. Cotton
is the best tobacco wicking material if you learn to observe the nuances of how your particular juice performs in it and learn to accommodate for them.
Rayon imparts a little bit of a sharp note, whereas cotton is a little softer.
Agree. But I believe its more a factor of
texture of the vape rather than flavor. Not a criticism, texture accounts for the majority of what we perceive as taste. It's a drier more diffuse output from Rayon, often hotter as opposed to warmer or softer accounting for that
bite you describe.
To my taste it can strip characterizing top notes particularly when over-driven. Some accents can seem to be totally absent accentuating the primary and abundant base flavorings. And that's just grand for some people, if that's their preference. Push it a bit and that can be heaven in that case. It is not the best for flavor accuracy.
For the latter, Nextel (RxW) down. Nothing feeds as efficiently as the coherent micro-capillary action of ceramic fiber or is as neutral to flavor.
Not advocating. Enjoy it all.
Good luck.