I owned a 66 H model for several years. Great airplane. As you noted, you hear all the hype about the early airplanes being lighter, which is not insignificant, for sure. But, as the airplane got heavier, it also got stronger. By the late 60's the airframe was basically the same as the 185. Consider that the first couple years of 180 were the same from the door post aft and the same wings, as the Cessna 170 B.
So, what is it you want to do? My airplane was a pretty stock H model, with an R engine, which most folks agree is one of the best if not the best of the 0 470s. It was IFR equipped, was a great float plane, a better wheel plane, and would go pretty much anywhere I wanted to go, and carry anything I wanted to carry.
In 1964, Cessna changed the fuselage over to the same design as the 185 in mid year. I flew an early 1964 model for a while at work, and it was one of my all time favorite Cessnas.
I like the G and H model 180's. Great airplanes. In fact, the 66 model I owned actually had a higher useful load on floats than the 1985 Cessna 185 I was flying at work at the time. Not by much, but....
Finally, the later 180's had the option of bigger fuel tanks. Those early airplanes are short of fuel, particularly if you go to a big engine like a lot of folks do these days.
Of the five airplanes I've owned, I rue the day I sold that 66 180. Shoulda kept that one. It's in Oregon now, and I hope the guy who owns it is taking good care of it.
MTV