That's pretty much my stroke, except I don't "open" my last three fingers in any dramatic fashion. I mainly use my thumb and index finger on the backswing and most of the foreswing, and on the actual stroke the hand closes around the cue upon impact. Even then, only my palm contacts the cue, not all of my fingers. The cue sort of "hits" my palm with a correct follow-through.
I've found that sometimes I pinch the cue with my thumb/index finger tighter than I would like, but the stroke itself remains straight and true. Compare our stroke to that of most Taiwanese players, who loosely wrap their entire hand (all 4 fingers!) around the cue, and twist their wrist slightly outwards in order to maintain a straight stroke.
Roger