Here's a short article regarding hackle quality: choosing hackle for fly tying
The "Turning Problems" section would seem to be the same issue addressed
in Frank Whiton's first video link. You might also note that the author points
out that some Metz necks have thick stems in smaller sizes, the same issue
I pointed out earlier.
If you have hen hackle, it won't float as well as rooster: fewer and softer
barbules. On the other hand, if you put enough floatant on, any pattern will
float like a cork bobber
When you need more hackle, look at the Whiting 100 packs. They are generally decent, and should be sorted by a specific hook size. Actually, there's a lot of decent rooster hackle available, and $25 will buy a nice
neck. Most of my dry fly hackle is grizzly, dun, brown, and cream. I buy the
cream in specific sizes, as I only use it for #10 and #12 flies.