My issue with the wooden ones I've examined in person, aside from weight, is that the chamber under the gourd, carved out of the wood, is not very large. A gourd is hollow all the way through. It's still a chamber, just I'd say less than a third the size.
I won't argue with someone calling a mahogany-body with meerschaum bowl, all-briar, or all-porcelain pipe of that shape a "calabash." The word has become a shape. But strictly speaking, "calabash" is the name of the gourd, and denotes a pipe made from said gourd.
You seem to know more about these than I do, so maybe you can shed some light on this. The bottom pipe above had a rim with no pins, so it came off easily. You can see what it looked like before I cleaned it, then after. So what am I looking at? Is that a meerschaum lining, or gourd? The top of the rim looks and feels like wood. I cleaned most of the 'paste' off of it and scraped all the cake out of the bowl. It felt like the inside of the bowl was meerschaum, but the opening at the bottom was irregular and too large (tobacco would just fall right through).