Thanks chas. Talking about wood, I tend to like the Abell blackwood whistle, anyway I liked the one I tried. Chris is telling me that his whistles have pretty stable tuning, not much different than his delrin whistles!
a former colleague of mine, a biological anthropologist, responded to my queries re good materials for whistles in this way.
he said that wood or polymer would be best in that they would not vibrate, whereas, he claimed, any metal, especially the lighter ones that one would be most likely to use, would vibrate and impart some degree of turbulence to the air flow, thus affecting the sound. the alternative, build a very heavy metal whistle to reduce vibration, would be problematic because of the weight.
my actual experience, which isn’t that great, is that there are an awful lot of tradeoffs. this fellow was replying off the cuff and didn’t really know anything about whistle physics.
so why would i ask an anthropologist about whistles? i dunno, he struck me as someone who knew everything about everything, and i’m no scientiest. 
I plum forgot about Abell. Plenty of oomph but not obnoxiously loud; nicely balanced across the octaves. I’m not thrilled with the sound, not being a huge fan of blackwood, but it just may be the easiest whistle to play that I’ve ever owned.