as for the cost effectiveness you already did ur calculations and you even concluded too.
as for the benefits - there are numerous - the biggest benefit is India will be on Global stage to act. If that doesn't ring a bell or if you think what's the use to be on global stage - then i really can't explain each and every detail on this MB. Today, millions of people wait in qs around the world to just visit USA and this deal is going to make India get closer to USA. What this means is the people of India can look for a better and good future in the long term. in order for the benefits to truly take shape .. one need to wait for 50 years. these are not short term benefits which u will see in the next couple of years. that's why this deal is very important for both India, USA and for the rest of the world too. That's another reason why all G8 countries are supporting it.