Yo' Guys,
Just like Todd, now that I have my own production Ikelite EOS300D housing I'm going to try a Canon accessory to see if it makes any difference in the viewfinder. Canon sells the EP-EX15 eyepiece extender and another DR buddy bought one. We both played around with it on the surface (I wear Rx glasses, he doesn't) and it did seem to allow better corner viewing. But we also thought it made the image look a tad farther away......
I'm also unsure if the slight increase in depth (spec says 15mm) primarily designed to get your nose off the LCD plus give eyeglasss shooters relief will prevent it from fitting flush against the Ikelite SuperEye viewfinder.
While many of us lament adapting surface finders to underwater use, the housing manufacturers all try to give us as much capability as they can....And we're all making photos with these tools. My mantra always is to try and go on more trips, spending more time in the water = great photos.
As I've posted many times there is a great TRUTH in VOLUME. And digital certainly gives us that!
Next step most people never learn or work at, editing.......I have one buddy who saves EVERYTHING 
See you below,
David Haas
davidhaas@sbcglobal.net