I'm not sure what snooker instructional material you read/saw but those that featured Gareth Potts and Ronnie O'Sullivan said the following:
Step 1: You hold the cue "normally" at starting position
Step 2: While pulling back the cue, loosen your grip. Two ways of doing it:
1. slowly releasing the little and/or ring finger (back release). This is the Gareth Potts way.
2. slowly releasing the index and/or middle finder (front release). This is the Ronnie O'Sullivan way.
Step 3: Stroke forward while tightening the grip again. The amount of power in the stroke depends on how much and how fast you loosen/tighten the grip.
Loosening and tightening your grip quickly creates a very fast acceleration.
Ronnie Alcano skips step 1, he starts loose from the beginning, but when needing power, he tightens his grip very fast during the forward stroke.
This way of using grip pressure to control power helps you deliver relatively the same stroke all the time. With exactly the same stroke, you can draw the ball 5 inches while dead-gripping and you can also draw the ball 30 inches if you loosen your grip and tighten it quickly to create acceleration. That's how snooker player plays.
I totally agree with the self-experimental way of playing, only you know what's best for you.
It's very effective. I break that way -- by grabbing right at impact. A lot of rotation players break that way. However, that's very different from shooting with a constant death grip.