First I have no clue what you mean by "generic dome ports" Each housing manufacture has one or more propriety port mount and while the port glass/ acrylic may be shared by some the mounting plates are not the same. Athena, Inon, Zen Underwater and others all make ports for several different housing manufactures products. Once you have spent some time on this and other U/W photos sites you should come to discover that Zen is one of the most well respected port makers in the business.
If you also do some additional research on the Olympus housings for PEN and OMD cameras you will discover that Olympus does not offer quality ports for many of its lenses and that several the ones it does offer are left overs from Olympus DSLR housings. Zen and Athena have filled this void with quality ports for many of the usefulOlympus lenses for U/W use. Zen also make the only optical glass ports for the Nauticam Mini housings. Since I use an Olympus E-M5 in a Nauticam NA-EM5 housing I find the Zen ports fill my needs quite well.
I have also test ports and other products from many other equipment makers so I think I know a quality port when I see one.
I don't own a part of any company.
Among other things I teach U/W photography workshops for Reef Photo, Digital Fiesta, Hasselblad excursions and others several times a year.
I also get the same discounts as all of the other photographers I know that are in the business.
Edited by Phil Rudin, 19 June 2013 - 03:20 PM.