Van, I have a big yellow pine in my front yard, so for a couple years I used pine straw and/or cones. It smoke pretty well, but burned hot, and the pine smoke was very irritating to me. A couple years ago I did some trimming on my apple tree and my flowering plum, and when the El Cheapo Harbor Freight chipper was done with the small branches it left a pile of chips about 3/8 - 1/2 inches apiece. One day I decided to give those fruitwood chips a try, and I was impressed with the results. It's a little hard to get started, but once gi=oing it is a sweet, pleasant smoke that I don't mind working with. Burns a long time, too.
I was just gifted a smoker grill and I bought some applewood pellets. I'm going to try your top down method on both the pellets and my homemade chips. I also don't see any reason why those chips wouldn't work in the smoker mixed in with the pellets.