I have been using interlock since I was a kid (15+ years) and I just switched to the 10-finger grip a few weeks ago. (see previous post)
http://forums.texags.com/main/forum.reply.asp?topic_id=2447089&forum_id=60I've never been consistent at striking the ball with my irons and tend to drop the toe end into the ground a few inches behind the ball. Since I changed my grip, I am now consistently striking the ball and actually creating a nice divot in front of the ball. I'm real good in keeping my left arm straight and pivoting around my right elbow, but never felt like I was getting any power through the ball w/ the interlock.
I think the 10-finger grip forces me to stiffen / flex my right forearm and allows me to more naturally roll my right wrist through the ball. I am now striking the ball at first contact and have a lot more power to follow through the swing, creating the divot and continuing with my front swing.
I am also noticing a slight pull with my driver / 3-wood, but as long as I visualize the follow through with the club head, I'm good.