Time for some mousse abuse updates.
I've put 4-5k on the Nuetech NitroMousse / Tusk D-Sport combo. That mileage includes the MABDR, the SM1K, several smaller off-road trips around western VA, and 2x long distance (200+ mile) runs at highway/freeway speeds (for reasons... Really didn't want to).
At this point, the tires, front and rear, are toast. The front is out of tread on 50% of the center knobs. The rear is mostly out of tread on the centers and starting to throw chunks / crack.
As for the mousse itself... I re-juiced them through the valve stems before the SM1k. In the beginning you could see some juice working out around the beads, but it still looked clear/clean. After the ride, the stuff being squished out is a grey-ish paste (never mind the sprocket, it has lived its life and will be replaced).
I have definitely noticed both the front and rear sitting more like it is at a lower pressure over the course of the last 1k miles, but still not completely 'flat'.
My impressions from absolutely abusing the mousse setup for the last year is that I don't have any reservations about using them for planned routes like the BDRs and whatnot. I am also willing to rely on them for running back home on an 'abort' mission, knowing that they aren't meant for long periods of tarmac.
Based on the external appearances of things, I'm pretty sure this set of mousse is done. I also think they would have lasted longer if I had re-applied lube more often and not had to make the long runs on pavement.
In the next week or so I'll get my act together and dismount this set of tires to get a look at the insides.