As said many times earlier, the Deutschland class cruiser was not a good combatship for fight against other warships, that were shooting back at her. Her value was politcal only. As a weapon there were much better ships in the German Navy, that were more ballanced in design. The larger Hipper class heavy cruiser was a better fighting ship, with better guns for engaging ships and more speed, if the enignes did not wreck themselves. The much larger Scharnhorst class battleship too was a better fighting ship, though not capable to engage an enemy capital ship, due to her smaller guns. (She was build to take a serious punishment though, like any battleship.)
Uhm... Hippers vs Deutschlands, well, at least let me be unsure about your claims. First, the engine: the diesels wrecking themselves? Okay, those were somewhat experimental, borderline revolutionary but still, the length and duration of the voyage taken by either the AGS or the AS at least have to be impressive and the propulsion worked fine. They had problems, of course, but IMHO, they were far, far away from wrecking themselves.
Especially in comparison to the Hippers. Correct me, if im wrong, but all of them have serious machinery problems pretty much all the time. And alltogether, the Hippers were bigger, almost 10 year later designs and with a hindsight, accomplished not much - as raiders, if i remember correctly, close to nothing. The Deutschlands IMHO at least led to the AGNA and made sorties at least embarassing the RN.
And yes, guns and political value. Pretty much anything naval had and have a political value and its an important thing. Indeed the difference between 28 cm and 20 cm guns are not that much, and at the same time, enormous: potentially dangerous to anything, deadly to the cruisers - Exeter was wrecked up pretty good at the battle - and their existence pre-war and during it at least messed with the thinking of the RN: the hunt for the AGS comperable to the hunt for the Bismarck in resources committed.
Anyway, long story short, i do not think, that the Hippers were better than the Deutshlands, with a hindsight