Imagine a scenario when performing, where you realise in a split second, that because of slight problems while performing the particular effect, you can either:
a) End up flashing the coin and hence everybody'll definitely know that that is where the coin was all this time.
b) push your pinky even more backwards so as to almost perform a vanishing pinky trick, hence nobody'll see the coin BUT they'll know something weird is happening (provided they notice the vanished pinky).
Which option would you say is at least COMPARATIVELY better in emergency situations?
I don't understand the scenario you're proposing. What's the emergency?
Presumably, you'd have thoroughly practiced the sleight and examined it in a mirror or on video to the extent that you are comfortable with the look and feel of it before performing.
The option that I gave in my previous post was to "drop your fourth finger slightly below the other three extended fingers". This was meant to be interpreted as a change of position of a millimetre at most; it doesn't take much distance to adjust the grip and position of the clipped coin. You shouldn't be anywhere close to doing a vanishing pinky illusion.
It's also worth noting, which I didn't allude to in my aforementioned preceding post, that the clipped coin most likely isn't held in position for an incredibly long time for the audience to notice it. It's also probably true that the hands will be in some motion.
If you HAD to compromise either on the invisibility of the coin or the angle of the coin being perfectly 45° or less, which one would you compromise on?
While I don't agree that this is a choice that should need to be made, the purpose of the sleight is to conceal the coin, and that should not be compromised on, especially in performance. Magic is entertainment, but the basis of magic as entertainment is convincing magic.