What a load of rubbish - this is a user forum and other users come here looking for advice, so nobody really needs to inform you of anything unless they wish to publish a comment.
If you are purchasing an expensive item such as an iPhone, the onus is on you to weigh up everything you have been told about whether the phone will work or not and then make that decision for yourself. Nobody else can tell you what to do and the onus is no on us (forum) members to tell you anything at all - it is only advice, but the final decision about buying is yours and yours alone, so if you happen to make a mistake and buy a phone from the US that won't work in India, then that is your mistake and you have nobody else to blame but yourself.
All you need to do is read the many threads on this forum about the same issue.
What you perhaps should have done is wait until the iPhone 5 became available in India and if you really wanted an iPhone that badly, then you should have gone to a country where the fully unlocked iPhone 5 GSM version was available for sale fully and officially unlocked - the UK iPhone 5 would be more compatible and there are always going to be issues with using US iPhones.
In the end you 'pays your money and you takes your choice' - your decision and nobody elses!