I love the use of heel in bodies. Especially as it gives bodies what I think is the right amount of life.
I now tie most of my dry flies with the use of that material.
I have also use Magpie but the best beyond doubt is Heron (a pick up while out fishing). I also use Rhea which has similar properties to Heron but is a light fawn colour.
Condor is also excellent but difficult to get. A substitute isn't quite the same.
I think this style of tying is largely unexplored as you see few patterns around.
Another think I like to do is to vary the colour of the thread and 'twist' two heels together and then open wind down the hook.
I get a lovely segmented lifelike look.
Here is an example from my parachute 'Kite'.

I have also use the flight feather of a Macaw Parrot to develop a Yellow May Spider:

This spider uses Rhea:

A Rhea:

So keep up the experiments and post them as I am interested and I am sure others would be too.