My KTM EXCs came with DIDs, my GasGas with Excels. In the same rocky terrain, the front DIDs on both KTMs were dinged after 1 season, but still well within service. The Excels on my GasGas are still true and dent free after 2 seasons. It may have something to do with bike/style, but the DIDs are fine and I wouldn't change them unless it were neccessary.
Havn't heard much about the new "U" DIDs for off-road, but they come on some of the new Kawasakis and all of the new GGs.