I run Scott's stabilizers on both my 2016 Xtrainer and 2011 WR250R. On the Xtrainer I'm using the BRP SUB (under-bar) mount and love it. It was easy to install and raised my bars a few welcome mm for my tall frame. The finished installation is very clean, especially when paired with the BRP handguard mounts that replace the handlebar top clamps.
On the Xtrainer the primary benefit for me is mitigation of spontaneous deflection due to rocks and roots on tight steep technical trails where wandering off isn't an option.
Here's an example of the kind of riding where I really enjoy the stabilizer:
https://www.youtube.com/watch?v=_ZJ6kadjEBIIt's not that I can't use my arm muscles to do the same thing but that saps a lot of my strength on a long ride, especially towards the end where I usually need it most. With the stabilizer I just seem to glide over these obstacles. For a while I was sharing one stabilizer between both bikes and occasionally was too lazy to switch it back and forth between rides. I was amazed at how I was taking it for granted, and how much more challenging it was to ride the same terrain without it. Sort of like the difference when riding a bike with a well-sorted suspension and then switching to one where the the suspension is just "okay".