Looking back at this thread, Roku has certainly improved since that time. (The cert checklist has been a web page for quite some time now.)
Technically there are some challenges with Rokupay; such as handling backend interactions from Roku -> your server and vice versa, and room for confusion. And to destruk's point, it is still expensive relative to other processing platforms.
But Roku is continuing to improve in all areas. Hey, I'm an investor too