Hey Texastroutbum, your axiom is the truth! A couple things: go to the Brodin website
and in the "news / info" section you can find out about the Ghost bags - those are the clear plastic "nets" -- you can purchase only the bag and tie it onto your current net frame (they offer instructions). It's a pretty sweet option if you have a solid frame, for $25 it's a big upgrade. Second thing, if you come to Montana to fish the Gallatin (GAL-a-tin) make sure you do not ask for directions to the Gellatin River!
Pretty sure you'll be sent somewhere far away.
As for shape of the net hoop, I am also curious as to why people choose what they do. In the end I think the most important aspect is practical - which shape appeals to your sense of aesthetics most and what size is best for your purpose.
But I do notice that the long narrow frame is often referred to as a "C & R" and not the teardrop hoops. I think this is because they are designed for the fish to lay relatively flat in the long, shallow net bag as opposed to the deep nets that curl the fish.