I would endorse pulling the chain, but only while I remain 65' or more away from the door, since the whole THING is a trap, which means there is probably a Golem on the other side of the door with a Symbol inscribed on it's chest. Furthermore, I would recheck the corridor for traps, as it is most likely that portcullis, or blocks of the ceiling will lower/fall/collapse to trap you in the room with the Peak-a-boo Symbol Golem.
In fact, I would at that moment recall that the rogue noticed strange seams in the stonework at the entrance to the dungeon, and retreat out with the important object, and send a summoned creature to pull the chain.
Because no one in their right mind would install a chain in a room which would set in motion a complex series of weights that would cause the entire dungeon complex to sink into the ground and collapse.
But then, whoever made the dungeon made a DUNGEON, so they can't be in their right mind.
However, I couldn't let such an exquisite Rube Goldberg dungeon go without being triggered at least once, which is why I would, with all due precautions, Pull That Chain!