I had a similar question a while ago and
made a thread that generated some good responses that may help you (updates on the last page) and the TL;DR is did make the change from an '18 to a '21 Comp. I did not track my '18 significantly so my experience is severely limited there.
Objectively the S55 is a better motor—more power, higher rev limit, and cooling isn't a limitation stock. I have done 3 days at COTA in the middle of the TX summer in 104º+ ambient temps and the car never skipped a beat—vmax was down to 144 from 148. I believe
OG Shark had pretty nifty N55 car with S55 cooling, but outside of that, I'm not sure if people have really conquered the N55 cars' issues of pulling timing on hot days or longer stints.
The broader question may be around the costs of changing and working around the challenges of the Comp's larger brakes which cannot fit 18s stock, and any mods you'll take a hit on because they can't transfer over to the S55.