User blog comment:DirgeOfCerberus111/Adeptus Custodes Vs. Grey Knights/@comment-2253300-20110819114042/@comment-10514705-20110819123329

I got to agree with Necrus on this one. If the war was fought anywhere except Terra, the Custodes would lose to the GK simply because they are trained as defensive warriors. However, they would be able to repel a GK strike against Terra with relative ease as they would not only have a better knowledge of their battle zone, they would also fight feverously to defend the Emperor, FAR more ferociously than the GK could even hope to fight. That is the thing with the Custodes, they are fantastic at fighting on Terra (during HH and Age of Apostasy), but without the need to defend their God-Emperor they would be lacking (despite being more powerful than a Space Marine).