Porro's are good optically but they are a small part of the market. I predict that since the manufacturers put most of there R&D money into roof's the porro will become extinct just like the dinosaur. I give them 5 years. What do you think?
Porri definitely have their advantages, namely light transmission number and 3D-experience at medium distance.
For people with big hands, like me, their ergonomic features stand out.
But the wide lateral prism housings obscure the part of the human FOV that sees outside the actual image of the binoculars.
As a result, I say their perceived FOV is poor compared to roofs. And the roofs are more packable and have better 3D representation at closer distance, because the left and the right barrel's image are more similar. The more widely spaced objectives of a porro unfortunately mean that a significant part of the joint view of the right and the left barrel is not actually binocular, leaving only a smaller portion with stereoopsis.
Quite recently, I aquired a FL 10x32. It beat the venerable Swift Newport 10x50 Mk II in every optical respect except for a slightly smaller FOV. Even the brightness of the FL is significantly greater.
So today I gave the Swift away to a charity second-hand store, and I have no purchase of a successor scheduled.
Never say never, but I can't see myself buy a porro again.
The porri won't disappear but their market share will continue to decrease. They will be available as lo-fi cheapy alternatives and high-tech astro bins, but will become even more scarce among birders.
Porro prisms are the only feasible solution for bins with large objectives, they are the ideal solution for straight birding scopes, and reversed Porros are better suited to close-up work than roofs.
They are still in demand in other areas outside of birding, so obituaries are premature.
John