Well since I own both of these balls I will comment on my opinions of each.
I have 3 of the Ebonite NV's, all 3 different drillings, all react differently.
2 of the balls are strong for me and the other is not weak but the weaker of the 3. Very good ball IMHO.
My Chalk is also strong. The reaction is kind of a skid/flippy roll, almost looks angular. I was watching a guy throw the new Jigsaw Corner and his Corner had a very comparable reaction to my chalk.
I like both balls very much. I would recommend them both if you are looking for a stronger ball. The NV I believe is a much more versitile ball because since I have 3 of them and 3 different looks on the lanes.
Like I said I would definately recommend both balls IMHO. If you need any more info on how either of my NV's react or my Chalk PM me.
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- Joe
http://BeansProShop.com