I have a variety of red window cameras, Voigtlander,Zeiss Ikon,Franka,Balda, Ensign to name just a few, also Welta TLR with red window, plus a few Agfa's some with the red window intact and some with the red window minus the ruby film, and I get no light leaks from any of them,and I use them in full sun, rarely close the slide, remembering that pretty much all red window cameras from at least the early 50's to the early 60's were desinged built to be used with panchromatic film I believe the camera designers/builders new what they were doing and would sell a camera that had light leaks from red windows, not if they wanted to go on selling cameras, I use pretty much nothing else for my photography for at least 15 years or more without problem, indeed.my first camera, when I was 9 years old, was a Brownie Starmite, for 127 film, cokmplete with red window, I used Tri x with it also colour film both Ektachrome and colour print without problems ( I still have the camera and for nostalgia's sake use it for fun once or twice a year, using 400 film, without any sign of light leaks,) so my personal conclusion is the light leak idea has been blown out of propertion, yes, I suppose very occasionly a problem might happen on a frame, but in general terms it simply is not a problem, at least in my experiance of using a variety of makers ove a lot of years