What made Riven and its like so difficult, even without inventory and only a single button to manipulate the environment, was the lack of information. There weren't any obvious goals or clues. Everything had to be figured out by performing actions and observing the results. So basically the absence of an overarching narrative and NPC given tasks had a direct influence on the difficulty. But Silence will have both, I assume.
Now, as another example take Night of the Rabbit. Personally
, I found that this had very simple puzzles (in that it was clear what to do and usually also where and how items could be used once you got hold of them). What made it hard was the large number of screens that were accessible and the number of simultaneous open tasks. But according to this interview
, the cursor will hold clues regarding the current task and if any items are involved, they will usually be utlilzed on a nearby screen.
In the first case, difficulty was increased by leaving stuff away that Silence will have, in the second case, difficulty was increased by adding stuff that Silence won't have. So unless there is some secret gameplay mechanic at work that raises difficulty, I'll continue being concerned.
Btw.: to me, Memoria had a fairly smooth progression of the story (i.e. it could have been a little bit harder). It should definitely not get any smoother than that :-).