I've seen a few computations like this, and it's great for estimates. But I would like to see the UI/tools just do the split from the beginning (rshares, reward pool, beneficiary+curator split) so it's accurate. Also more people are using services (dtube, etc) which have beneficiaries so that would need to be taken into account also. Well of course steemit does to give us that number but it should be easy to tweak to show estimated split.
That said, this is a good thing that more people should know about.