Of course there is a difference between human test positions and practical computer games. Nonetheless hash tables will show effect in both cases. How much effect only depend on the actual given position and even more on the way HOW the programmer told his engine to make use of this tables. I am no programmer and can't explain how the one or the other system works, but i guess you will agree that nowadays PC engines use their hash tables in a different way than DCC's. There are differences inbetween DCC's, too.Oh, i saw the comparison between Atlanta and Milano Pro before, but now i think it is time to mention, that there are more differences between Atlanta and Milano Pro (Master Chess) than only the hash tables. At first, the Atlanta's hardware is noticeable faster than the others. At second, the Atlanta has a later engine version. If you compare Atlanta to Milano Pro (Master Chess) it is something similar like comparing Fritz 3 / P90 vs. Fritz 2 / 486-100. Of course the Atlanta don't has Fritz 3 as engine - i just wanted to explain in an example, what you are trying to compare.

Kind regards, Wilfried