Using external links, like google, I discovered that the FWFT FIFO is the same meaning as Altera's Look Ahead fifo. Basically the D_out is valid when empty /= '1', and so read_en acts more like an ACK rather than an enable. In a normal fifo you have to assert read_en to get the d_word on the next clock.
FWFT/look ahead have a combinatorial output rather than a registered output, so timing usually results in a lower fmax. the pro's/cons will depend on whether you want the read_en to behave like an ack or a read_en (basically, its 1 less pipe delay).