Banal exchanger btc to real money but with investment platform, what you think ?
Well there are a lot of BTC -> FIAT exchangers, but never saw one with investment platform. How do you expect to pay back to the investors? I mean, the only way you can profit from an exchanger website is on the fees and exchange rate. So with an investment platform you would need to increase fees and have bad rates. Correct me if i'm wrong.
Anyway, i think to be successfull you would need to make a simple and minimalist website. No signups, no verifications, no headaches. Something like: User lands on main page, select the amount he would like to sell (in BTC), selects the payment method (this is another concern.. some e-wallets like paypal, skrill, neteller are instant, although they may limit your account and you would need to suspend your services for a while.. but you have the non-instant payments like SEPA, wire transfer, western union. not sure what payment methods you are thinking), the exchange rate will show and how much user will receive, and then a confirmation email with order ID and a link to follow the transaction maybe.
Good luck.