In many ways I prefer porroprism binoculars. The design is a simpler, less exacting, solution to the optical problem, and simplicity has much to recommend it. In theory, you should be able to produce an exceptional quality porroprism glass for considerably less than an exceptional quality roof prism glass. The main drawback has always been that porros are more difficult to weather and waterproof than roof prism designs. Often the added cost of waterproofing makes high quality porros just as expensive as high quality roof prisms.
The Swarovski Traditionals are a case in point. They are everything great porro glasses should be‹waterproof, optically exceptional, rugged, well armored, easy in the hand, stable and well balanced‹but they are not significantly less expensive than the roof prisms they compete with.
Swarovski asked me, specifically, to compare the 10X40 Traditionals with the Zeiss 10X40s. The Zeiss glasses are probably the single most popular binoculars among what we might call "high power birders." The Traditionals are optically every bit as good as the Zeiss 10X40s. I actually find the porro body easier to hold in the field than the slimmer Zeisses, and, after my move to Maine, I would easily pick the waterproof Swarovskis over the Zeiss binoculars for extended field use.
In this particular comparison I have no problem saying that many birders would get as good, if not a better view with the Swarovski glasses. I could easily see myself using the 10X40 Traditionals as my primary birding glasses, something I can rarely say about any 10X binoculars.
It is more difficult, however, when you compare the Swarovski Traditionals to their own roof prism siblings. The Swarovski SLC 10X42s are my current Reference Standard for high power binoculars, and among my favorite all around birding binoculars of any kind. Before extended testing of the Traditionals, I would have said that the SLCs were the only 10X glasses that I would have considered using as my primary birding binoculars. They are still, at least in the two samples I have for testing, just marginally sharper than the porro glasses, and they are also exceptionally easy to hold and to hold steady. They are, however, considerably heavier than the Traditionals, and the Traditionals are somewhat brighter.
I think, in the end, that weight and brightness just might be the deciding factors here. The SLCs are still my favorite 10X glasses, but for those of you who might be thinking they are just a bit too heavy, and are considering sacrificing the waterproofing for a lighter glass, you should really take a good long hard look at the Traditionals. Then too, if brightness is a real concern, if most of your birding is done in deep forest, or tropical jungle, the Traditionals should give you marginally better performance. You might find you could live with old-fashioned looking binoculars after all.
