Even barring knowing that backstory, Finn knows that none of the other Stormtroopers will give so much as a moment's hesitation if ordered to kill him, as – not a single one of the other troopers on the dropships sent to Jakku so much as hesitated to gun down the civillians, and they'd be even MORE motivated to kill a known traitor.
How does he know that? If he can break the conditioning while keeping up the masquerade, so can other people. He can still kill to survive, he just shouldn't be so happy about it.
I never said it was the same thing. In fact, she only flies the Falcon once on Jakku, and then only takes it into Hyperspace later to find Luke with Chewbacca as a copilot. That's it. She spends more time tinkering with the mechanics of the Falcon, and bypassing the modifications done to it more than anything - which was my point. She's far better at knowing how the Falcon works and last second fixing things to make it a more capable piece of junk than she does to fly well with it. For example:
• Her initial takeoff is incredibly sloppy. She has to bail out of the Star Destroyer's super structure through a hole because she's out of her element. She's unintentionally skimming the ground a lot, during her initial escape.
Despite some fancy (Force assisted) maneuvering, she's not an amazing pilot any more than Finn is an amazing gunner.
She outflies two professional TIE fighters in an unfamiliar craft (one she dismisses as 'junk' before they take it.) They're flying low on purpose to confuse the tracking. Yeah, it's not perfect, but for a literal first attempt that's incredible. Anakin and Luke do get some plot armour in their first movies, but they don't pick up force powers and lightsabre duelling on their first try as well as their established piloting abilities.
One - He's playing with Finn after knocking out Rey against the tree, because Finn was a traitor and Kylo Ren WANTS to take him out. It's the shortcoming that he feels frustration over because he noticed him on Jakku, and didn't take care of it then and there. He toys with Finn, and only when he gets nicked slightly does he get serious – at which point he absolutely DESTROYS Finn.
You don't toy with somebody when you're that seriously wounded. Kylo Ren is badly hurt, we know that much, he has to stop and hit himself several times just to keep going. But deliberately prolonging the fight isn't something someone barely still on his feet does, he should be ending things as quickly as he can before he passes out.
Going back to ESB, Vader makes his 'join me' speech after Luke is disarmed, not mid swordfight. All they had to do was frame it a little bit different, Rey disarmed or on the ground while the speech is made. That way, her closing her eyes for ten seconds isn't as questionable, and she gets a win without making Kylo Ren look bad when we're supposed to take him as a major, if immature, threat.
. The greatest thing that sucks about intellectual property rights that favour rich corporations is that some of these fan theories will never see the light of day by independent film creators 
. I have a feeling the sequels will simply not live up to some of the awesome ones I've read. Disney will take the safe road. We all know it 
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