A friend has a Vow & is looking at the Eruption Pro. He is wanting to know if he drilled the E Pro the same as the Vow, would it be a good step down from the Vow or be too similar.
Vow layout is: 60 x 4 1/4" x 45( 4 3/4" x 4 1/4" x 2 3/4").
Or would something like 50-55* x 4 1/2" x 30(4 1/4-4 1/2" x 4 1/2" x 2") be something better for when he wants to move in deeper, when the Vow reads too early or labors down lane?

he is a tweener, high tilt, lower-avg rev rate & speed is matched. thanks!

I would have to say my Vow and Eruption Pro cover around the same amount, but the Vow picks up more in the midlane and the Eruption Pro is mostly all in the backend.  Now your friend could always take the cover on the Eruption Pro down to 2000 and it will let him move in deeper that the Vow./

I also have both, the EP is at 1500 + light polish (300 rpm )
the EP to me needs some up front head oil, if the heads have friction, it seems to read way to early.
More of a tournament ball to me at this point
the vow does read earlier, but more continuous overall the the EP

got my BTM right here
length 16
hook potential 47
breakpoint shape 15

I dont see those numbers in the article.
i had the good fortune to have this as a test ball (i know someone who knows someone)
drilled it pin down, roughly 4.5" pin-pap, it slowed down to fast for me on THS conditions
re-drilled it pin up, same pin-pap I think, still had that same characteristic.
Ball needs some oil to get down the lane, when the conditions are right, that ball stores a massive amount of energy while maintaining a very predictable continuous motion.
futzed with different underlying surface prep and it is more of conditional piece for me at this point.
when its right tho...watch out, its that good