I have been building custom rods for 17 years, and a split grip offers ZERO sensitivity improvement. It's only potential advantage would be blank contact and I have never seen anyone hold the exposed blank.
I have also ben told "I like it because it lightens the rods". Removing weight behind where you hold a rod only makes it more tip heavy, and thus less sensitive.
Removing the fore-grip has a slight advantage, as you are removing weight ahead of where you hold.
Cork is very expensive, and rod companies save a ton by using split grips/no fore grips - and good marketing allows them to get people to jump all over it.
I am only sharing what I believe to be facts, no personal opinion. But hey, this is fishing. We have all week for the "have to do stuff", when fishing time comes, use what you like - if it's good quality it will catch fish. :)