That's true, but with a forcing deck as the kicker, you get to tell the spec that you know what they're thinking. That all the cards must be the same. Then you get to admit that it's true and show that they are identical, just not the spec's card. If it's signed, the setup of them all being the same is instantly dispelled and becomes random clutter that's not needed.
I'm just wondering, what do you think is going through the spectators mind when they see the blanks? Do they think "wow, it must
have been my card going through the deck the entire time because they are all blank." OR "HUH? Where did he get a deck with blank faces on them? Did it start out that way, or did they lose their faces during the trick?"
Honestly, I think it's the second one. Why? Because I tested it out on a layman. At first they were surprised at the blankness, but then it look like they entered a state of confusion. One of the things the said was "wait, cards aren't printed that way? Where did the faces go?"
I think that it might be stronger to initially
show the entire deck blank and only have one face card then do the ACR. Wouldn't that be stronger?