Re: Rod Grip: Thumb or Index Finger?
I too cast mainly in the thumb-on-top grip. I will sometimes go with the 3 point grip (or slight variation) when going for distance but for one main reason, it helps prevent the rod tip from swinging to the left (I'm a rightie) on the longer back casts.
If you take your hand back in the thumb-on-top position you might find it natural to have a slight twist of the wrist that in use tosses your reel outward and the rod tip inward. Slightly rotating your wrist counter-clockwise so a vee is formed from your thumb and index finger and placed where your thumb usually goes in the thumb-on-top position can help in preventing that looping, left-to-right 'wow' of your line when going for the long shot.