Mrek, it is not enough to just lay the index finger over. You have to dig the middle finger edge of the index finger down towards the center of the ball, dig it in hard. It makes all the difference in the world. Young girls hate that grip when they first start with it, it is not comfortable at all. They hate until they see what it does in a game then they love it.
"Batters hit them out of the park all the time." The cut rise, oh yeah, pounded hard all the time. The bent fingered rise thrown with some practice, hardly ever hit hard. It can be thrown much faster than 60mph and still hop up and still be caught. But you better be experienced at it or be prepared to take shots off the mask.
She does not lay her finger on the seam. She digs in hard. When she is throwing well, her index finger will be substatially bigger than her other fingers. she calls it the "fat finger" but she knows it accompanies some decent riseballs.
Sorry, but I am in the camp that doesn't believe in "hop".
"Hop" to the batter is an illusion.
I do believe the rise "falls slower" than non-backspin pitches.
If you are 6-6", you probably were hitting near or above 80MPH. (My DD can get the rise to 60MHP)
That velocity makes catching more difficult, but not because of the "hop". Just less reaction time to location.
Add the velocity to the visualization from on top of the pitch and I believe you and the batters would "see" quite a "hop".