I used Rayon for a about a year, and have been doing Koh Gen Do for about 6 months.
I got a good deal on the genuine stuff on ebay. Something like 40-60 pads for $10, I forget.
Rayon and KGD are very comparable as far as flavor goes. The rayon gives you a better nicotine hit though, and it lasts longer than KGD for me. I vape a dark, sweet juice and with rayon I'd have to rebuild every 2-2.5 days. With KGD, I can't even last a full 2 days, vaping about 3ml a day.
I thought rayon was easy to work with, but KGD is even easier. Also, the concerns about the man-made material with rayon. I dunno, I'm used to KGD and rewicking every day, so I just keep using it.