I only had them installed for about three weeks before I had to undergo a longer planned surgery, so no, I have not used them off-road. Just once on a fire road with some potholes, some gravel and hard packed dirt.
The bike tracks much better with the front now, but the Tiger 800 Roadie has pretty bad front suspension to begin with, for my weight (72kg) I found the F800GS better when comparing stock to stock. The Traxxion is better than either of the two stock bikes. Much better when on bumpy backroads, that I tested very well so far.
What I wanted: adjustability and the component based system Traxxion has, so I can remove it from the Tiger and use it in a different bike after a not too expensive re-work.
To gauge it properly, I'll have to replace the OEM rear shock, too, as this is also a cause for some grief.
Regarding weight, I'm a fairly minimalist packer, so max weight I have used with the Traxxion cartridge installed was around 20kg luggage (topcase for day to day stuff, Ortlieb Rackpack for clothes). No difference to the overall impression.
What might interest you: I was using about 90% of the fork travel of the Tiger 800 over a few hundred miles (put a zip tie around one leg and let it there for some time), since I have the Traxxion installed, the ride is smoother and more comfortable and I have only used about 70% (or slightly less) of the fork travel. Meaning it gives me more reserve, while still being more comfortable.