Disclaimer: what follows is my personal, strong opinion. Yours may differ.
For what it’s worth, I think a lot of the higher end whistles are more trouble and price than they’re worth. Most whistle players of an advanced calibre (that I know of) play whistles with very low backpressure, but virtually all the ‘high-end’ whistles that people extoll on these have backpressure that is medium to high. I, as well as the whistlers I know, feel that this really removes a lot of the grace, speed and flexibility of the instrument in an effort to cater to less experienced players with difficulty in breath control.
I’m not making a value judgement on these instruments, but commenting that I, and other experienced players I know, find them perhaps less than a perfect fit. Honestly, I like my dad’s old Generation more than anything I own, but that may change in the next couple weeks.
“High-end” whistles I’ve been impressed by are as follows:
Jerry Freeman: Jerry does awesome things to cheap whistles, making them excellent instruments at an unbeatable price. I use his stuff for basically every key except C.
Pat O’Riorden: These are hard to find, but if you can get one used they’re almost unilaterally freeblowing, air-efficient, and have excellent tone. Bit loud, though.
Jon Sindt whistles are also quite good, if occasionally more scratchy in the low octave than I personally prefer, but with good intonation and nice medium volume.
The most recent iteration of Carbony mezzo A and Bb are quite good, fantastic tone, design and easy to grip. Can’t speak for their higher whistles.
Also, I’m going to post some clips of the Noah Talmadge whistles I’m receiving soon. I had the occasion to play one of them at the Cascadia irish week, and was smitten. He’s a brand new maker, but very, very promising.
Final thought, after playing many of them, I have to say I’ve rather lost my liking for Copelands. I think some of the earlier ones I played had more character than his later work.
Anyway, obviously whistle tastes differ from person to person, but I think a serious student of this music should avoid overly high backpressure, as it often becomes a crutch and complicates things later down the road.