Those using brads hopefully have them long enough to go through Homasote and into the solid substrate. We have found short brads that only go into Homasote will eventually work their way up, to a hazardous result with passing trains.
We do use brads to position the track, the once the ballast is installed and glued in place the brads are removed. The track does not move with even high traffic on it. Seasonal movement is then more or less matched between the substrate, roadbed and track.
