Here's the promised comparison between the old and new data. Despite the base terrain resolution being the same in both cases (3" or roughly 90m spacing), the new dataset comes with much better erosion shapes that were previously rather washed out.
The new data come from multiple sources, mainly the original SRTM data and data from Viewfinder Panoramas that provide enhanced data for Eurasia. It appears that the old data were somehow blurred, and fractal algorithms that refine the terrain down didn't like it.
The difference shows best in Himalayas - the screens below are from there, starting with Mt.Everest.
old | new
There are also finer, 1" (~30m) resolution data for some mountainous areas of the world, and we plan to test these too - interested to see how it affects the size and changes the look.
→ forum link