Some comments on the proposal:
(1) Very short learning curve: It should take maybe a couple of minutes for someone who knows both Hindi and Tamil to learn the schema.
(2) Obvious interpretation: It ought to be obvious even to someone who has never seen the system to interpret the letters in the new system.
(3) Compliant (technologically) with multiple platforms: this system is very easy to type with on a standard Tamil keyboard. It is also very easy to type with when working with web applications like Quillpad.
(4) Helpful for minorities: it is very helpful for minority groups; for instance, to be able to avail of social services such as getting prescriptions filled appropriately. (Rather than mess up the name of a medicine; one could write it without loss of fidelity in this system).