I saw this recently on vacation and decided to blast a bit on my normal cruising levels.
Sure, you get a bit of an ache, but it's dirt cheap, and very clearly real.
I even used the BD harpoon that it comes with.
Well... this is from a few years ago.
I didn't get any of that, and I used 3 amps the first day of vacation and 3 amps the last day.
Yes, you do get a bit sore, but nothing unusual from a ~3cc injection (it is shy at about .7ml per amp).
And it is clearly real. The prop hit me like a ton of bricks.
My poor wife was limping around worse than me.
Sadly... I won't be escaping the center of the US for a while.
So no luck in giving it a try.