I will believe all this seams crap when I see it. To me, this is the NCAA's way of saying "Sorry, we went too far."
I think it will hurt pitchers more than anything. Those Holder type curve balls will not have the same bite with lower seams. I think that will lead to more contact but I don't believe it is going to drastically impact the HR numbers. I will gladly admit it if I am wrong but I don't think I will be.