Don't have WT library at my disposal presently, but in the Reasoning Book it insists that the NWT is to be appraised on its own merits, that it is "an accurate, largely literal translation from the original languages. It is not a loose paraphrase, in which the translators leave out details that they consider unimportant and add ideas that they believe will be helpful. As an aid to students, a number of editions provide extensive footnotes showing variant readings where expressions can legitimately be rendered in more than one way, also a listing of the specific ancient manuscripts on which certain renderings are based."
Ironically, in view of this latest KM, the RS book also goes on to say this:
"Some verses may not read the same as what a person is accustomed to. Which rendering is right? Readers are invited to examine manuscript support cited in footnotes of the Reference edition of the New World Translation, read explanations given in the appendix,"* "and compare the rendering with a variety of other translations. They will generally find that some other translators have also seen the need to express the matter in a similar manner."
*which also reference secular and religious scholarly (non-WT) materials
It should be noted that the RS book was designed to be used with the public by reading the answers to Householders' questions directly from the book. Thus it is to be expected that there are stronger statements of the NWT's supposed superiority contained within other literature. In any case, the belief that the NWT is superior is implicit in WT publications, and most JWs credulously accept the idea.