Thats me in the video link you were provided. (That was my first go at making videos so I must update it sometime as I want to improve on it).
My simple advice to you is to try some of the basic techniques in there and see what you can get to work for you. Practice practice practice. I used to practice in the walk-in-wardrobe at home, or in the car (on my own of course) at the traffic lights when going to work. It won't take long to get things to happen if you just try different movements with the whistle.
Until you get tone that you want, be sure to blow the whistle hard and loud. Short and loud for minor infringements and long and loud for PK and try.
No I haven't - I'm generally pretty happy with my whistle volume, tone and variation so feel no need (not that I have the best whistle tone etc). I have been trying to get hold of a polycarbonate one because the metal ones get cold here in winter. I also have heaps of the 58.5, as a sports store closed down a few years ago and they were selling them for $5, so a grabbed a heap.
I have seen the 58... Maybe next time I see it in the shops at the right price then I'll grab one to give it a try.