Trying to decide between 67 and the 645. The 645 is more modern as far as metering, TTL, etc. but I love the larger 6x7 negative (that's where the largest gains are found going up to medium format anyway). I like the 645's 75mm and 135mm leaf shutter lenses as compared to the 67's 165ls (and the discontinued and hard to find 90mm ls) considering half of what I will be shooting is people. The 67 is built like a tank. How is the construction of the 645? Is it 'plasticy'? How do the lenses compare? And, is there any truth to the rumor of a new 67?