I’ve heard from someone that amongst many good qualities the Copelands just feel good in your hands. Perhaps due to the conical bores? Do the Burkes also have that same good feel? I never found the feel of the Chieftains very appealing. Is the feel in your hands of an Overton the same as a Chieftain? I’m specifically speaking of low whistles here.
I can’t imagine the “feel” of different whistles being too significant if the weight, diameter, material and shape are the same. I would imagine, and I could be wrong, that some of the difference is mental. The only differences I have found would match the above, including the finish. I have never held a Copeland low whistle, and imagine it would have a nice feel to it. I have also heard that because of the conical shape, the bell note is also further away from the second. I personally like the feel of the Chieftain Golds I have, in part because of their weight. I’m talking low F here. I might not like the low D though since it might be too heavy. I really like the Songbird Low D for it’s lightweight and very smooth, polished finish. But, that’s my preference. If anyone would like to send me a Copeland, Overton, or other nice low whistle to see if I like . . . 
Part of that Copeland feel is the weight. In all sizes I’ve tried, they feel very substantial, especially if you come to them from lightweight whistles like Sweetones or Generations . Also, the surface including fingerholes is very smooth which feels great.
That extra weight can be a bit of a disadvantage. I was having a really hard time playing my D for a long time until I epoxied a saxophone thumb rest onto the back of it. Big help.