The only way to know if the "dummy chute" was actually a dummy chute would be to open it. That wasn't done on the plane, so it begs the question of how important the chute was, or knowing if it was a legit chute.
Besides, he couldn't attach it to anything so for me it is unlikely that Coop used it as a chute.
It is plausible that he used it to descend from a tree, though.
I have to disagree on a couple of very important items here Bruce.
First, if the dummy reserve actually had a red "X" affixed to it (not at all certain if this is true) then Cooper could have easily recognized the dummy reserve as just that. Furthermore, according to Cossey the dummy was not packed as tightly as the genuine reserve and this was apparently noticeable to the touch. I do not know why this would be the case if none of the shroud lines were removed. Perhaps 377 could weigh in on this.
Second, Tina Mucklow testified that she saw Cooper attempting to fit the ransom into one of the reserves. In fact, the size differential between the ransom bank bag and each of the reserves is obvious. In other words, merely observing the bank bag next to the reserves would be enough for Cooper to recognize that he couldn't fit the bank bag into a reserve.
However, Tina testified that this is what she saw. I believe what she actually witnessed was Cooper putting a "portion" of the ransom into the missing dummy reserve. The reason for this is that the bank bag could not be properly secured without removing several of the packets of $20s...it was too full.
Later, I surmise that Cooper, landing near Tena Bar, buried the bank bag along with these excess packets of $20s that were crammed into the dummy reserve, on the beach at Tena Bar. Later, under cover of darkness, Cooper returned to retrieve the bank bag and the loose packets of $20s buried in the sand, however, three of the loose packets were accidentally left behind.
Let us remember Sheridan Peterson's comments about the dummy reserve being daisy-chained inside.