When he left Hinduism, was he rejecting India or a system inside it?
A system, and he was at pains to say so. When he chose Buddhism he chose a faith that began in India, and he made the choice a claim on Indian history rather than an exit from it. He argued that the Untouchables were descendants of Buddhists who had refused to conform, so that the conversion was a homecoming to an older Indian tradition. He ruled out Islam and Christianity on precisely the ground that they would, in his judgement, move his people out of the civilisation they belonged to.
So the rejection was aimed at a doctrine of graded inequality he had spent twenty years trying and failing to reform from inside, not at the country or its past. He kept the country, its history and much of its inheritance; what he set down was a specific ordering of human beings by birth that he had concluded was inseparable from the religion as practised.
This is why the conversion reads as an argument rather than a renunciation of India. He was still, at Nagpur in 1956, working out a way to be fully Indian and fully equal at the same time — which is the same problem he had set himself at Mahad in 1927.
In the Journey: The speech that was never delivered, 1935–1936