I've made all sorts of stuffed mushrooms, and they were always pretty good, but there was also always something didn't quite taste good to me.
Finally, I read somewhere, that it's best to saute your mushrooms in olive oil or a bit of butter a bit before stuffing them.
I tried that, using just enough olive oil to cover the bottom of the saute pan, and a couple of tbl of butter. It only took a few minutes, and it really made a difference in the taste. I didn't get that raw mushroom taste that I usually get from stuffed shrooms.
Just a tip...you might want to give it a try.
We get by with a little help from our friends