I was wondering if Desmognathus brimleyorum does better in a more aquatic habitat? This seems to be the case from what little I have read, but there is such a scarcity of info on the net about this particular dusky sal.
They are pretty aquatic. I've had the chance to see them in the wild a few times as well as keep them. Smaller ones are often under rocks in the middle of the streams, larger ones tend to be under rocks on the sides of the stream rather that really in the water. I kept them in about 4 inches of water with a good current and lots or rock rubble for them to crawl around on.
The natural creeks where I've found brimleyorum were no more than 1-3 inches deep with very fast-flowing water, perhaps 1-1.5 feet across, and a very sharp incline. Very small stuff. I think a Paramesotriton-like setup will be too a little too still for them. They'd need some really agitated water because they asphyxiate really easily. One or two of those big airstones work nice. The juveniles seem most aquatic, the adults seem to like the stream/bank interface zone though they'll still prowl the deeper water occasionally.
Good luck with them Ed, they're a really neat species.