Is there any advantage to replacing your white rice or wheat or oats with more exotic or less delicious grain?

Short answer: No. If you are eating enough ragi, quinoa, oats or any other grain to get a notable amount of protein, iron or any other micronutrients from it, you are probably consuming far too many calories overall. 

If you are doing it for reasons of speed of digestion (GI etc), you are better off combining rice with a lot of vegetables and dairy and/or pulses. 

If you are doing it for reasons of taste, eat the grain your tongue craves. 

If you think you are intolerant, feel bloated, uncomfortable or allergic to any grain including but not exclusive to wheat, find some other grain which works for you. 

You don’t have to give up white rice. Just measure and eat what you love. You can still get to whatever body composition you desire.

PS: We know potato is a tuber not a grain but it’s an apt comparison.