between two O-6s, are we not moving off the mark of the thesis presented in the OP ?

That is, are there significant differences, which can be used to our (US) advantage, in the approaches taken by Sunni and Shia groups in developing strategy, operations and tactics used in the armed conflicts in which they have been and are now engaged ?

The Executive Summary of the CTC report seems to think so (I reformatted to separate the bullet points):

There are significant and little appreciated differences in the trajectory of Sunni extremist terrorism and that of Shi’a extremism. The differences exist across six key areas that impact American policy considerations, especially in light of steadily escalating tensions with Iran.

First and foremost, Sunni radicals and Shi’a extremists differ in the overall approach and main objectives for their use of terror. The former tend to operate in a continuous, mid‐to‐high intensity manner, seeing war against infidels and apostates as a perennial condition featuring overlapping waves. Outside of an ongoing and seemingly open‐ended campaign against Israel, terrorist attacks by Shi’a groups have by and large featured discrete terror campaigns tethered to state and organizational objectives.

Second, Sunni terrorists and Shi’a extremists manifest different patterns for recruiting terrorist operatives and developing terrorist missions. Shi’a terrorists, unlike their Sunni counterparts, enjoy direct state support and for that reason are far more likely to originate from Iranian embassies, consulates and state‐run businesses.

Third, despite holding a minority viewpoint within the wider Sunni Islamic community, Sunni extremists, especially Salafi‐Jihadis, rely more extensively on the support of their coreligionist expatriate communities in facilitating terrorist activities.

Fourth, while employing similar tactics and methods, Shi’a terrorist groups have shown a much greater propensity to kidnap innocents to barter, while Sunni extremists more frequently abduct to kill.

Fifth, Shi’a terror groups exhibit a much higher incidence of targeted assassinations for specific political gain, rather than the high‐casualty killings featured in Sunni terrorism, and particularly of the Salafi‐Jihadist variant.

Finally, each sect’s extremists manage publicity and propaganda differently. The Sunni approach to information management tends to feature doctrine and resources geared to take immediate credit and widely amplify a terrorist event. Shi’a terrorists, while not averse to normal media publicity and amplification, by and large take a much lower‐key approach.

Importantly, this study does not argue or imply that violence perpetrated by Sunni or Shi’a extremist groups is carried out for reasons that are inherent to one or the other tradition of Islam. There is no evidence sought or identified in this work contending that historical patterns of terrorist attacks by organizations identifying themselves as Shi’a, for example, are pre‐determined by Shi’a theology or philosophy. What this study does suggest, however, is that those Shi’a organizations that have conducted terrorism in non‐combat zones display several preferred operational patterns that contrast markedly from their Sunni counterparts.
The general thesis of this report is similar to the arguments advanced by Bob Baer in The Devil We Know - several dozen reviews at the Amazon page.

PS - George: Your six points are something you and I could spend much time into the wee hours of the morning; but, for the life of me, I have a hard time seeing how they are directly material to the thesis of the CTC report.