Honestly there's nothing special about IRGC. They just get a massive budget compared to the regular army and other agencies.
Some would argue they're more motivated and that may be true but the disparity in budgets can't be discounted.
Recently they were able to put a satellite into space when the Iranian space agency failed. This gave the IRGC an image boost and people were saying "hey look they can get things done when others cant"
However looking into the details, the payloads of their satellite was a puny 12 to 24 kg. The Omid satellite from 2009 was around 24 kg and the space agency can has since placed 50 kg satellites into space (like the Fajr or Navid satellites for example)
The space agency has had some failures recently but they are striving to put a 350 kg payload into space and with each failure they have progressed through various stages. Last time only the final stage failed to reach the required speed.
It was not my intent to discuss whether there is something special or not about the IRGC, nor to engage into comparisons with other institutions. Much rather, I raised the question whether or not new fighter jet acquisitions from either Russia and/or China might in fact be intended for the IRGCAF. And if consequently, the IRIAF will be left to fade out once its legacy inventory is no longer able to be refurbished. Personally I do see several potential long term benefits in this.
One recurrent counter-argument is that of systemic institutional and doctrinal inertia which would render impossible a transfer of the center of gravity of Iran's air force from the IRIAF towards the IRGCAF. But as I observed above, institutional inertia is a reality however it can be overcome in 43 years provided minimal political will.
It's like the often peddled myth that IRIAF personnel and officers tend to be more distant vis a vis the revolutionary establishment. Again, who is naive enough to believe that in 43 years, a political system - no matter its nature, would fail to replace personnel as needed in a strategic branch of the military..? Fact is that IRIAF pilots and commanders are surely every bit as hezbollāhi and velāyatmadār as their brothers in the IRGCAF.
However, for certain organizational and other reasons, I would welcome some gradual merger or take over by the IRGCAF. One of these being, for instance, that Sepah is particularly shielded from the whims of changing governmental administrations as far as its budget is concerned. Therefore, the more areas of activity the IRGC gets involved in, the more we can count on progress in said areas independently of politicking and fluctuations in financing. The reduction of the ISA's budget and the subsequent slowing down of Iran's space program under Rohani is a good example of why and how Sepah can compensate for relative setbacks like these.
This said, to address your remark: the IRGC definitely is a unique type of a military and paramilitary corps. Actually its area of competence as per the Constitution reaches well beyond military affairs, since it is tasked with combating any threat to the Islamic Revolution, knowing that these threats are multi-pronged and located in a multitude of realms: social, demographic, cultural, economic, political, diplomatic, cyberspace, public health, soft war, social engineering and so on. Hence why the IRGC has a legal mandate to operate in all these fields simultaneously, hence its specificity. And thus the IRGC has no proper equivalent outside of Iran.
And as for how the IRGC has fared so far when compared to other institutions, the realization that Sepah appears to get things done in a particularly systematic and methodical way, that they are consistent in their mid- to long-term planning, that their procedural chain from design concepts to mass-produced items is solid, did not just dawn on people after they successfully carried out their first satellite launch - this became obvious right from the early 2000's and the astounding development of Iran's ballistic missile arsenal, one of the country's key assets of deterrence against military aggression by the zio-American empire.
Another point that makes Sepah stand out is how proficient it has shown itself to be in doctrinal and technological innovation. In thinking outside the box, adapting resources, weapons and tactics to Iran's asymmetric needs, in completely doing away with conformist thinking as well as with any attempts to try and reach a semblance of parity with Iran's powerful foes in the latters' own playing field. There's little doubt that the IRGC, more than other involved parties (whose contribution I certainly do not wish to deny) has been the central driving force behind Iran's thorough shift towards an asymmetrical type of reasoning in the military arena.
Hence why it is also the IRGC that is focused on, demonized and sanctioned the most by the existential enemies of Iran.
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launched a satellite on a missile that was twice the size of the missile that civilian agency used more than 10 year ago to launch heavier satellite
Obviously, this is to say that the IRGC's SLV is capable of placing into orbit greater payloads than what it did during that launch. Furthermore the entire operation was aimed to demonstrate technologies as much as to fire up a new satellite. Sepah's SLV with its solid fuel and thrust vectored stage(s) is also more advanced. Sepah's launching method and protocol allow for better security against potential sabotage attempts by the enemy; as a matter of fact, Trump didn't have the opportunity to parade silly satellite pictures of the IRGC-conducted SLV launch like he could do with the failed Space Agency launch.
So here the IRGC's achievement is undeniable. With regards to space launches, Sepah literally came out of the blue, surprised everyone with unsuspected capabilities and hitherto unseen technologies, succeded on their first try.