For me, I have found that I simply cannot change the way I hold a cue. The reason is that if you change the way you hold the cue in a standing position, but use the same Pre-Shot Routine to "get down" on a shot, then your grip on the cue may be only slightly altered or not even altered at all, as your body will naturally use a grip that is facilitated by a certain head, foot, and torso position.
If I want to change my grip, I will start by changing the position of my feet. For a long time, I was all twisted up, and it was hurting my game. lfigueroa from this board noticed it when we played, and he made a suggestion about changing how I addressed the shot...I took his advice...my game took off.
I think we make a mistake when we try and talk and think about grips, head positions, elbows, etc. like they are parts unrelated to each other.
Also, I think holding the cue towards the back can help with power. Some say it detracts from control. I am not one of those. I hold the cue about 5 or six inches from the back. Something to consider is that most cues with wraps are developed from the model started in the 50's, 60's, etc. with Mosconi, Crane, and that crew. A lot of those guys played in a more upright position than modern players. I am not saying one is better than the other, just if someone is upright, their back arm will be further up the cue. Conversely, if they are low their back arm will be further back on the cue.
Hope this helps.
Kollegedave