I personally stayed in India for a while and been diving in Goa (west coast), Pondicherry (east coast), as well as the well known beautiful Andaman's islands. Honestly, i don't recommend liveaboard divers to dive in India, even in the Andman's Island.
On the mainland of India, there is not yet liveaboard trips that can be offered. There is only one liveaboard called M/V Infiniti offering long a week liveaboard trips around the Andaman's Island.
The diving itself in the mainland of India were just for diving, nothing in particular i've seen compare to other destinations, right now the diving in mainland of India is not really amazing.
For the Andaman's Islands, i would say it's a bit more worth to dive. There are some nice reefs, but the fish life are still average, the visibility was between 5 to 18 meters. Compare to Similan Islands in the Andaman Sea, the Andaman Island in India offering much less fish life and corals than Similan Islands.
For divers who used to go for liveaborad trips i could say for that similar places like Similan Island, Maldives, Seychelles will offer you much better diving conditions.