"main stream"
Note how you used quotes. Spoken like a true ignorant shippingfag. A pairing is more main stream because it has a bases to it, as I was kind enough to provide examples of. Making it not on the same level as retarded shipping, e.g. Crack. This is basically common sense, and you not knowing it says a lot.
yuri of a story
This is code for "I have zero standards". "Yuri" itself can not be good or bad, if the writing is good the yuri good. Yuri is just a genre, it has no value, and you thinking it does just shows that you only judge something based on whether it has yuri in it or not. Even though you claim to care about the writing.
And yes. Crack pairings lead to out of character writing, such is the case here, which is bad. If the characters are not acting like themselves it defeats the purpose of the doujin parody itself. Unless of course you're just looking for characters that look physically similar, but that again leads back to having no standards.
http://exhentai.org/s/dbd0f95212/670419-28
I've actually read both, and I can say for a fact the NaoRei one is better. While this MiyukiRei is just pointless OOC sex the NaoRei is sweet.
Of course I'm probably just wasting my time typing this out because you'll just dismiss it as the paranoid ramblings of some angry guy over the internet. Arguing with shippers is one of the most pointless things in the world.