As an Amiger, I'm entitled to one eagle feather (I call it the "rudder") and I wear this behind my clan badge (Keith)....HOWEVER, I only do this on very rare occasions such as games where there are others whom are armigerous. The point to that is, we tend to clique up and harumph about nonsense that nobody else would get. Beyond that, I think it makes me look twattish and overly self impressed. I do NAE wear it in Scotland, as I get quite tired with the questions and accusations. I do not take my standard with me, and certainly do not keep a wee copy of my matriculation on me. Advice is simple...in the US, do as you wish, it really is of no consequence...in Scotland, leave the plumage at home. As far as hackles, I have a brother in the 3rd of the 42nd, and have been given by him a red hackle to wear behind my fathers Watch bonnet badge.
Honestly, I think a smallish pheasant feather looks rather toffish, but that is just me.