The few times I have used Dwaynes they have always did a good job with development, but if they are mounted backwards then they will be reversed if you scan or project them, as far of the quality of handling and service, Dwaynes is well known, but if they were mounted improperly, I would let them know...
By the way, how did you verify, they were mounted backwards? I am just curious, it is pretty easy to see if they are mounted wrong..
Several of them seem to be backwards because the emulsion side is on the lettered side of the mount on some, but on others the emulsion side is on the non lettered side. Also, the orientation of some images differ from others. The actual quality of the development seems fine though. I scanned them all (had to flip a few to get the correct orientation) and I was pleased with the colors, exposure, sharpness, etc. I purchased several more rolls and plan to shoot them tomorrow. This is my first experience with Kodachrome and I am thrilled! And yes, to add to the cliche, I plan to shoot several rolls with my old Nikon F2A! Now if I could only find an older Nikon F to shoot my Kodachrome with, I would be happy according to Paul Simon!