Although I prefer the LaFontaine Emergent Caddis, I tied a lot of flies, when I lived on the Missouri River in Montana, that left the overbody off because they were much quicker to tie; thus, I was able to make a bit more money by tying them that way. There were several others I knew who did the same; however, none of use ever called it anything other than a simplified LaFontaine Emergent Caddis. This was back in early 1980's.
And yes, it is nearly as effective as the LaFontaine Emergent Caddis and I think a bit more effective than Matthews X-Caddis because it rides lower in the water more like an emerging caddis. I used to carry LaFontaine Emergent Caddis and Troth Elk Hair Caddis in many sizes and colors when I lived in the trout paradise known as Montana. I never carried the Matthews X-Caddis because although good, it was not as effective as Lafontaines Emergent Caddis and Troth's Elk Hair Caddis. A person could do far worse than tie the "Miracle Caddis on their tippet.
As an aside, I would run into Gary quite often on the upper Clark's Fork River and sometimes on the Missouri and Big Hole Rivers. He was a great guy who always enjoyed his time astream. His knowledge of caddisflies was astounding.
I've also had the priviledge of running into Al Troth on the Big Hole, Jefferson, and Beaverhead rivers. He was always a gentleman and these chance meetings were most pleasant.
I was also fortunate enough to see Troth, LaFontaine, and Charlie Brooks among others tie the flies for which they were well-known in the years I lived in Montana.