They do offer there blanks to the custom rod builders.
The whole split grip design isn't about looking cool it is for better senceitvity. If your rod feels to tip heavy you just need to balance your rod by putting some weight in the back of the blank.
I guarantee you the same rod with split grip and non split grip in your hands you cant tell the difference in sensitivity don't fool your self buddy :-X :
Well I own both split grip and full grip rods and there is a difference its not a huge difference. So don't fool yourself buddy.
So do I and rod builders have clamied it makes no difference they use split grip to save on cork cost, and because customers fell it's m0ore comfortable. In fact a full grip balances the rod better which a balanced rod will feel more sensitive Bud,
The price of cork is peanuts. The are not saving that much maybe few dollars depends on the quality of the cork. The st. croix legend is any where from 220 to 270 so you think they made it a spit grip to save money on cork you are nuts. A company like st. croix or lommis get the cork for pennies. Think what you want.