I've been running one since fall of 2013 on my lbz. I read all the same negative comments you did, and I can say that after 20k miles nothing bad has happened to my motor.
I made a thread way back when I put it on, but my stock balancer looked like total garbage and just plain looked worn out after almost 200k miles. so maybe a new stock balancer would have been just as good as an aftermarket one? who knows, but I think I said it before- I actually forget I have a Fuildampr most of the time because the truck is so smooth.