I am an OCI and perhaps my views might be of help. I obtained British nationality, which effectively meant, I had given up Indian Nationality Status. India allows Such Indian Nationals who have obtained some foreign nationalities obtain Indian Nationality . So, I am a British national with Indian Nationality being my second nationality.It is not Dual nationality since OCI status is not Full Citizenship.( there are some restrictions explained below)
1 - This allows me to visit India visa free and stay in India for as long as I want, without restrictions.
2 - Exempts me from having to Report to Foreigners Regional Registration officer / Foreigners Registration Officer or Local Police Authorities if I am going to stay for longer than the basic 2 or 3 weeks.
3 - Gives me NRI status which helps me deal with my personal, financial and economic interests in India as normal NRI.
4 - I can purchase Residential, Commercial, Industrial properties(except defence)but there some restrictions on buying Agricultural and Plantation properties.
5 - I cannot vote in India since I gave up that right when I gave up my Indian Citizenship. I cannot contest any elected role in the Government of India or hold any constitutional posts like that of Governor, President, Vice President or the Judiciary - Supreme or High Court Judge.
6 - The OCI status allows me to work for any private company and study at colleges and universities without the need for Work Permits or Student visas respectively. When I have kids, they too can avail facilities in India to study for any courses.
7 - OCI status allows me to avail Housing facilities run by the Government.
FOR PIO card Holders.
1 - Visa free travel to India for 15 years. Basically a long term visa.
2 - No need to obtain Student or Workpermit to study or work in India.
3 - PIO card holder does not have to register at the local Foreigners Regional Registration Officer if visit does not exceed 180 days.
4 - NRI status in Financial, Educational and Economic aspects.
5 - PIO card holders can buy and sell Residential land and commercial property, but they cannot buy agricultural land.
In my opinion, obtaining an OCI status is better than having a PIO card. The facilities are better and lesser complications. The only important aspect you have to remember is, whenever you travel to India, you have to carry an additional card, which is a grey coloured Passport with just 2 pages. This OCI passport has your OCI Nationality on it and the replica of this is stamped/Pasted on your US passport as OCI visa. Without this additional passport, you will not be admitted into India by the visa officer. It is the same for PIO card holders too. They have to carry the PIO card when visiting India. So, this is an additional requirement.
Please let me know if you need anymore information.
All the best.
(Rated by 3 Council Members)