Now that my Steam Deck LCD has been relieved of his duties as a daily driver desktop PC, I finally went ahead and replaced the Delta fan with a Huaying one. It turned out to be relatively easy to do ; and lo and behold, it is indeed quieter.
Recent adopters may or may not know there was a medium-sized kerfuffle about disparities in noise profiles of early Steam Deck units. It was proved and narrowed down to a difference between 2 fan models (see Gamers Nexus detailed analysis).
Obviously the one I got was a "bad" one, emitting a high pitched noise when running at full speed. I did not find it unbearable but it was still not ideal, particularly when using the SD in quiet environments.
Took me 2 years to get to the point where I figured it was an acceptable risk to attempt the replacement. How many of you did the same and kicked the Delta out of your unit ?
I usually run the Fortified armor passive to help survive the rocket spam. Against the Incineration Corps, it is as you surmised the Inflammable passive that will grant the most survivability. Since you do not have any armor with it, you might be able to fall back on the Acclimated passive. If you have neither, well, you will need to be very quick on the dive.