Things are often just a matter of perception, but having been a member of MR for over 1 1/2 years, and owning both a K1 and a Sony 505 (and preferring (slightly) the 505), I can honestly say..
I perceive absolutely no bias in the moderation of MR for either Sony or Amazon.
It is the Cybook they are obviously biased toward!!
No seriously, why would they be biased toward any device? They are only interested in readership! They have nothing to gain by any bias. That would only limit their readership.
And the moderators here are a diverse group with a wide range of devices that they use.
I think you are perhaps just overcome by the recent excitement at the launch of a new device. The same intensity exists whenever a new device is released. And it is short lived.
Then we all get back to unmentionable silliness and foolish folderol.