Just a simple question: what is the point of holding OMA?

Since both of your markets will accept BTC is there any reasonable logic behind paying with OMA (which has 0 liquidity and volume) compared to BTC?

Do any of the OMA investors get any bonus features?

At the moment the only point of this coin was to give you the ability to crowdfund on an altcoin exchange and gather BTC to be able to start and maintain your darknet market. If you don't launch a coin you can not crowdfund on the altcoin exchanges and nowhere else could you gather money for a darknet market. People buy your coin and can pay with it on your market, but no one can make the merchants actually accept OMA over BTC. And since OMA has no liquidity and market no one will pick it over BTC.