Okay, I've read the reasons behind your logic. But I'm not completely convinced.
How was the Chamber ever logically easier than the Shrine? Think about it, at least you knew where all 3 monkey pieces were, because they had assigned spaces. Now, there were no assigned spaces for the Markers in the Chamber, and therefore the room was conceptually harder. My case in point is all the contestants that started to blindly feel around the Chamber walls for the projections that were the Markers, because they blended in so well.
Also, even though no Guard emerged right when you entered the Chamber, there was always the outside (or in this case, inside. LOL) chance of the Guard being hidden behind the drop door. It was harder on the nerves of the contestants. Can't say that about the Shrine.
Well, it was easier in that 1) the pieces were a lot less trouble to transport and 2) there were only so many incorrect orientations that could be attempted, and only a few were ever tried because of the patterns on a couple tiles. Few contestants, if any, ever messed up on the ordering, whereas some players have tried to use the head instead of the torso in the Shrine, or the torso instead of the base... It's also harder in that the pieces are well-hidden, obviously— look what happened in "The Lily Crested Crown of Clovis I," for example.
And how does the Shrine win on the second point? The extra shock factor was good for the Chamber, IMO— I bet even Mitchell would've been rattled by a guard there if he'd competed in Season 3.

The Chamber of the Sacred Markers: +4
The Shrine of the Silver Monkey: -4
The Chamber of the Sacred Markers 309
The Shrine of the Silver Monkey 195
#10: The Holes of Python
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#7: The King's Storeroom (Season 2)
#6: The Dark Forest
#5: The Room of the Secret Password
#4: The Room of the Ancient Warriors
#3: The King's Storeroom (Season 3)