I stand corrected, I thought the III had a 1:1 finder too! I have the IIIa which has this brilliant big VF and is real 1:1, a pleasure to use. The only quirk is the advance lever which is rather odd.
I only wish the III had the big VF. The one I have was my grandfather's; had I purchased rather than inherited it, I would have gone for the IIIa or IIIm just for the finder. The advance is a little peculiar, but the lens is great and overall the camera is built like a tank. I find the advance becomes second-nature after shooting a roll or two in succession - something I rarely do with it these days, unfortunately.