The author is saying that &>word and >&word are both the same, and both equivalent to >word 2>&1. In addition, the first form is preferred, though no reason is given for this...

The author is saying that &>word and >&word are both the same, and both equivalent to >word 2>&1. In addition, the first form is preferred.

The immediately following text in the manual says why:

When using the second form, word may not expand to a number or ‘-’. If it does, other redirection operators apply (see Duplicating File Descriptors below) for compatibility reasons.