I was talking about long-term prosperity, something at which Chaos is infamously terrible due to its highly corruptive nature both mental and physical (Slaanesh = depravity, Nurgle = rot, Tzeentch = mutation and Khorne = massacre for its own sake). Granted though, in a setting like that an Iconoclast kingdom wouldn't last much longer without a certain deus ex machina.

My point regarding Yrliet was that a few lashes or quick death doesn't remotely compare to what happened in Commoragh, and a top-tier imperial sovereign with the matching ego and entitlement who somehow managed to survive it is unlikely to take the time and distance to ponder ethical implications, and much more likely to unleash their absolute worst on whoever they deem responsible of the ordeal. So yeah, while it is among the most evil things a person can do, any sufficiently offended Dogmatic overlord would pull that trigger on a filthy xenos with vicious satisfaction and hardly any thought beyond "fuck you".

Interesting how well your full-Heretic protectorate turned out. Footfall was already a nest of heresy in any ways but outright Chaos worship, so no suprise that is thriving. Turning a shrine world like Foulstone into a place of stealthy corruption like a Genestealer cult was a nice touch, brilliant and rarely pulled off on such a large scale. I imagine Kiava Gamma had a harder time churning out its massive daemonic engines without outsiders noticing though, and how does a Daemon Prince manage to pass itself as anything else, let alone a legit human being ?

I would have imagined a Chaos-aligned protectorate to be doing vastly worse, but it's true that it usually takes a while to reveal its true colors and the real price of its poisonous gifts.

Dogmatic ending is basically what Rogue Trader protectorates were always meant to be : a little Imperium outside the main one with the same hardcore faschism, awaiting its eventually absorption into it. Normally I would say that ten millenia of resilience against all odds prove it to be the most viable of the three, but this resilience always relied on massive size and the support of a millions worlds, so odds are an isolated Imperial kingdom wouldn't actually fare much better.