They'll get a fair gain from just not having reheat, yet alone the rest of the benefit of decades of aerodynamic design around engine exhaust flows.
(I didn't know and had to look it up)
Consider the difference between a large shop fan, and a small high pressure compressed air nozzle commonly used in workshops for cleaning, with both sized to give the same "reaction force" (i.e. the same thrust). The high-pressure nozzle makes much more noise.
Monocrystaline fan blades have very different material properties from the polycrystaline blades that (I am guessing) were used on Concorde.
https://www.americanscientist.org/article/each-blade-a-singl...
One of the patents mentioned is how VerSnyder was able to grow a turbine blade in a monodirectional crystalline structure: https://patents.google.com/patent/US3260505?oq=versnyder+196... just using a special mold and a specific alloy. That would later form the turbine blades of the SR-71 Blackbird.
