Would using funds to invest in a start up business of someone who is struggling financially qualify for Ma’aser Kesafim?
Would it make a difference if we have it set up so that any eventual profit sharing would go back into the organization to be used for addition chesed projects?
Using money to help start up a struggling business (or a business for somebody struggling) is certainly a valid use for maaser kesafim. As the Rambam writes, the highest form of tzedakah is giving the poor individual a parnassah — such as by starting up a business for him.
However, maaser kesafim must be given as a donation, and therefore a clause must be made that the money is not refundable, but is given as an outright gift, or, as the question suggests, that it (and profits thereof) should go to some other charity after returns are given.