You're right the size difference isn't much nor is the weight, and the LTM Leica's are more limited in practical usage than say, an M2 or M3. Only with external finders or guesstimation can you frame anything but a 50mm on the Leica LTM cameras. I have a iiic but honestly its kind of a novelty for me, just not as easy or versatile as my M Leica's in use. The ltm lenses are still worth looking into though..