One thing I've noticed between baseball and softball leg guards is that baseball adds an extra "plate" between the knee and the thigh cap. I'm guess because the ball is smaller.?. Since she's moving out of the 14.5" shins, it looks like we'll be forced to use the baseball shins if we go with All-Star. It may be a nominal amount, but I'd hate to add any weight and especially bulk for no reason. It looks like the Pro-Motion claim to fame is that they do away with the thigh cap all together.
My DD went from 14.5 to 15.5 All-Star legs without any issues. There's a little weight gain due to the increased length, anyway. I don't think the extra knee cap adds a whole lot more. It's not like they suddenly feel like bricks have been added.