I have to admit there was a time when I tried to replace Partridge with Grizzly, and a few shades of Brahma hen. I learned the hard way, there is no substitute for partridge (in my opinion). That being said, there have been times when patterns with Grizzly hen could not be substituted with Partridge. The hen capes have their own merit, and I stopped trying to compare them to partridge.
There are a few drainages, the upper Gunnison River being one that Grizzly does very well for me. Especially with the Olives. I added a muskrat thorax to this pattern after I saw some other patterns displayed on this forum that had gray added. I can not see the addition of the muskrat being a negative, but, there was a time I thought I could substitute hen hackle for partridge and get away with it.
Thanks folks for the positive feed back.