Hi Chris, I hope that this finds you well.  Earlier this year I purchased a Fasst Flexx bar for my DH bike and I wanted to provide some feedback.  
As I believe I mentioned before,  I came to this bar from a variety of aluminum and carbon bars and after a day or two in the park I suffer from all the vibration.  I have some tendinopathy in my right elbow that typically surfaces after a day or two of park riding and if I don't take immediate corrective action (ice/stretching/backing off/shorter days) it can get worse in a hurry.  I mounted the Fasst Flexx bar to my DH bike and immediately rode 6 consecutive days with zero issues whatsoever.  The only thing I noticed was the lack of any sort of issue.  I've since logged a pile of days, some of them pretty long, and have had no issues with my elbow, fatigue, or arm pump.  While it doesn't completely erase braking bumps (I can't imagine that anything would), this bar allows me to focus on riding rather than managing how much vibration I'm subjecting my arms to, and I don't have to think about taking less rough trails toward the end of the day due to fatigue or buildup of aggravation.  They really are the business!
Because the bars kind of stick out and draw a lot of attention, I make sure to stop and tell anyone who will listen how much these have changed the game for me.  So many people have issues with grip/arm pump[/various other issues and are eager to hear about a potential solution to their problems - something that will alleviate pain and just let them ride.  Generally the follow-up question is "how much do they cost?" - and while they aren't inexpensive I always make a point to tell them about your 30-day money back guarantee, as well as asking what they'd pay *right now* to be able to ride pain free.  This is particularly salient in a global riding destination like Whistler, where they've often spent thousands of dollars to be there for a few days/week.
In short, I LOVE these bars!
Khai-North Vancouver, BC