Try chiff and fipple - there'll be more reviews of whistles than you can shake a stick at.
But my ten pennorth:
I have played with Clarke, Shaw, generations, Susato and Dixon whistles and generally prefer the raspier sound that the tapered metal whistle provides. So Shaw and clarkes get my thumbs up (although I found Clarke whistles need some playing around with to get the sound right). This is just my preference.
I do agree that the Shaw whistles tend to take more air to blow (but it's not that much more)than cylindrical bore metal instruments. For the price they are a good whistle (especially the low G and A whistle).
I also have a Bleazey wood whistle which I adore - the notes given by cross fingering come true and the tone and volume itself is so much more better and clearer than i have ever experienced with a metal whistle, but it requires significantly more air than the Shaw whistle. However, the benefit is that I can even hear myself at a very loud session.