"1. The original makes me feel disoriented"
Not really placebo now that I think about it, the rockets come from a different origin
"2. I can't hit things with the original."
Not really placebo now that I think about it, the rockets come from a different origin so aiming wouldn't be "exactly the same"
"3. Raw Input makes me aim feel different vs Windows 10 + MarkC Mousefix (http://donewmouseaccel.blogspot.com/2010/03/markc-windows-7-mouse-acceleration-fix.html)
NOTE: I have heard that there is some evidence pointing to the fact that Valve's raw input has unavoidable smoothing, this one may actually not be placebo."
Raw Input between 7 / 8 / 10 isn't different, so Placebo. Your Note is true though.
"4. Toggling my viewmodels on and off changes my scout gameplay"
Somewhat placebo, turning them off allows you to see more, having them on brings your eyes toward a point to focus (usually). So personal preference, but not placebo.
"5. m0re's config feels a lot smoother to me than chris/comanglia's."
Might be placebo (their's so many things going on here that it's really hard to say)
"6. Placing my forearm on the edge of the table and keeping my arm straight gives me better reaction time and higher APM than resting my palm on a palmrest/the table."
This has a lot more to do with sensitivity settings. People with low sens really shouldn't have a constant palm rest, also it's bad on your wrist if you have a palm rest.
"7. Claw grip gives me way faster reaction times"
Depends on "Way faster" 5-10ms sure (it easier to reach the actuation force necessary from a claw grip than from a palm grip), but much more than that is definitely placebo.
"8. The Null-Void Movement Cancel script when used in a certain way is a game-changer for scout. The movement patterns I create with this allow me to play on-par with and sometimes even beat scouts in DM and MGE gamemodes with hundreds of hours more than me, despite only having 30 Hours on scout."
Placebo, honestly I think the null-void movement scrips actually makes scout slightly more linear. You completely loose the ability to stop instantly, which can be a bad thing.