All ...
Instead of challenging to the "doubtful" tips from the OP or bs comments here I've decided to try using fingers for my forehand looping (not backhand yet) in the last 2 days. Well .. it is very hard! Hard to control and be consistent. I guess I am in the 50's (2000 level player) so it is tough to teach an old dog hard tricks. BUT .. I've found the forehand loop was stronger and spinier. My practice partner didn't know I changed the grip (I didn't tell him) and could only block 3 times before the ball popped out of the table. Hey folks .. it works! Then I watched Ma Long's videos from someone here demonstrating the finger technique and am now convinced emratthich's (translated: I like very much) tips are valid. Hey folks .. let's give him some credits for bringing this topic up.
His tips are hardly doubtful, but are definitely not for beginners unless you consider a 2000 level player like yourself to be a beginner - anyone who has followed table tennis to some degree has heard something like them in one context or another. THe first time I started seriously messing with my grip was when I went to Nigeria and a coach told me that I Was holding the paddle wrong and showed me 5 or 6 different grips, all with a focus on the thumb and index finger when I asked him how he had such great touch and said that my grip was categorically wrong. I was already USATT 1700 at this time.
Here is Ben Larcombe on grip (there is a video there as well). Ben Larcombe is easily 2000+.
http://www.experttabletennis.com/grip-experimentation/
Here is a Henzell video and you can see the way he asks you to keep the grip and what he does when he encourages you to do it:
When I asked my coach (Brett Clarke), who takes a zen approach to table tennis, he said that no one could honestly report to you precisely which fingers helped with which shots even if they tried their best to. What you do is try stuff, look at your ball quality and make adjustments over time. When I argued with someone on mytt over how to hold the paddle correctly,Brett told me that there are lots of options for grips and even discredited ones can be used. He said that these things will become clearer over time with personal experience and that while there are general rules, there is no magic way. Since he does believe in whippy strokes, this was the video he made on grip tension:
One day, we had a laugh because a famous pro (currently top 20 and was top 10) was using a grip that had an element that Brett said was not correct (and no, I do not mean Danny Seemiller).
Are these interesting issues? Yes, especially for advanced players. Are the things that beginners should focus on? Not really. Many players get to a high level both in China before these issues become relevant for them. They are usually things that players can try to work on their output with the feedback and guidance of a coach, not just random tips people share. A good coach with experience trying this kind of stuff will actually talk you through some of the common errors and the process so you don't get frustrated when or if it doesn't pan out for you.
Since I have spent 4 years working on grip issues, I can tell people that you need to be relaxed enough to facilitate whip and be flexible enough to create racket angles that give you multiple options for handling spin. With practice and experimentation, it will come together. But what is relaxed enough? Other that Brett's video on being relaxed enough to play whippy strokes, I really don't have a more precise answer. I remember someone focusing on the three lower fingers based on the advice of a Nittaku site, and then another player said that Stellan Bengston had taught him with the three lower fingers as a focus and I reviewed my grip and noticed that I did a lot of things with the three lower fingers that I often ignored (likely because I had already heard the focus on relaxing them and using the index finger and thumb). And even using the index finger and thumb, I had to develop strength in them over time. And later I noticed that I sometimes had better shots when I reintroduced the bottom three fingers for certain shots. Now, I have my own grip which is a regular shakehands with my own modifications which is informed by the experience of hitting the ball in various ways to get different effects.
So experiment with your grip. But don't be fooled that some Chinese secret will automatically make it better, especially if you are a lower level player. Advanced players, at least USATT 1600, are the ones who will begin to gain the most from grip experimentation.