Good video my friend.
The questions you have asked, I too have been thinking about plus add another 3 wrist positions and hand actions to the mix.
I have come to some conclusions, right or wrong.
The 1st grip you show, I find it works best on power shots in straight line but doesn’t work well on draw, more of a stop shot hold.
Deadly accurate but no real feel or finesse.
If I try to slow down the stroke it loses accuracy and same thing happens it is hard to keep straight.
I’m much lower on the shot than you are and it makes it easier.
When I try to play with this hold I position my elbow, shoulder and hand in such a way that they cannot go anymore right.
This way I can make a mistake only by pulling the cue towards my body. Much easier when you miss to one side only.
The 2nd grip, interesting thing about this grip is that you can push your hand out which brings the elbow more towards the body creating a plane that allows stroking in a straight line with ease.
However, like you said cannot go back too much.
I experimented with this hold and rejected it.
I like the elbow in this position but not the wrist, no real touch.
The 3rd grip is the most accurate, Efren has this type of a hold.
I believe it is easier for you to cue like this because your hand cannot physically go anymore right.
You have created a plane and you are staying on it.
The cue rests on your fingers and isn’t getting pushed left or right.
The danger is that the bend in your wrist can change.
This stroke is great for soft touch, draw. Not so good on follow shots, rail shots, jacked up shots.
I find you can guide the cue the longest on a straight line with this grip.
I have 2 grips that I have been experimenting with:
For straight follow shots, rails shots, any shot requiring perfect straightness where cueing is the most important and the CB doesn’t have to do anything fancy, so shots with no English.
I like to hold the cue by wrapping my middle finger around the cue.
2 back fingers are off the cue.
Thumb and index pointing down, the tops of index and thumb hold the cue from side movement and the top of this contraption presses slightly down on the cue.
This completely immobilized the wrist, without chocking the cue.
For draw and finesse shots, it is kind of like your 3rd grip but much less bend.
Once again for me the middle finger is the key, I use it to stabilize my wrist from side movement. There is some support from ring finger, pinky is off .
The thumb points towards the body somewhat, not down.
The index finger is sort of on and off the cue.
If you watch the index finger of Archer or Immonen it is sort of like that.
The cue delivery is very level with this grip and follow through is the greatest.
Another benefit is that if you want you can start your stroke very slow and accelerate at your leisure.
Anyway, it’s just me.
The wrist position and holds are largely determined by the alignment of the other parts of your body.
Some grips work better with certain stances.
Relationship between shoulder, elbow, hand dictates the most what type of grip will be effective for you.
Just another player trying to figure what works.
Good Luck!