I am not a professional nor an expert photographer, but I have worked with triplets and tessar lenses on my folders and I can rarely see much difference between the two in my images. Based on my experience the Super Ikonta with the Tessar, the Bessa with the Color Skopar, the Billy Record III with the Solinar all produce great images within the f/5.6 through f/11 aperture range. Though not 6x9, even my old Agfa folders with Agnar and Apotar lenses can produce great images within that same range. If you enlarge to far they are all a little soft wide open. If you are not worried about that all of them will do a great job taking pictures as long as the lens is clean and they are focused properly. Although I do scale focus with some of these inexpensive folders I am very conservative, usually using the f/5.6 scale when shooting at f/11. I also usually don't enlarge the results much past 8x8.
Though far from an expert, what I can tell you is that it is pretty easy to tell the difference in quality between my large format folder pictures and my 35mm pictures. Even an inexpensive 6x6 folding camera, used carefully, will easily show far more detail and quality than a comparative 35mm camera. I love my M-mount rangefinders but my Agfa Super Isolette will always shoot better pictures. Using the camera is certainly not as convenient, and you can't swap lenses, but if you have the time the pictures are always better.