Dragon Rush actually was quite useful from my experience, but the real problem is that the game has changed a lot since the analysis was written. This analysis is become more and more dated (though the main body of info remains unchanged).
Frankly though, this analysis might itself become moot if Garchomp gets banned from OU this round (or if Sandveil does, because until Rough Skin comes out it'd amount to the same thing).
I think any further work on Garchomp (either here or in an update) should be held off until the results of this OU vote are finalized.