Did the chicken come before the egg?
Another one of life's great mysteries.
Until the beginning of the spring, I had been using the Thunderer 63 - very small and very loud, but a little too high pitched. On the advice of an assessor I replaced it with another larger whistle, one with a deeper tone - the 58 mentioned above.
One week later, I was given a 58.5 (I needn't have bothered buying one), but being a semi-supersticious person, after having a distinctly average first outing with it (as I tested it), I went straight back to my recent purchase of the 58 (which I had previously performed admirably with).
I don't personally have a preference between the 58 and 58.5, both very good for rugby, but I do miss my 63 because with a large crowd it cut straight through the noise being very loud and of a slightly higher pitch - not the best for rugby though.