You do not want projections, you need a reasonable forecast based on solid evidence. You should expect to see it in writing, preferably in a prospectus. You should ask an independent accountant to look over the numbers with a critical eye. You also need details of how often returns will be paid to you, whether they will be a steady flow of income or a lump sum at the end of the investment. The tax bill you are saving today might simply be put off for a few years and become a really big bill if you actually get the return promised.
Tax is a tricky area.
Also, if there is no income from the investment, you might have to pay back taxes. Remember that your money is going to be much less safe anyway, and so if it is all going into this scheme you will be taking a really big risk, compared with someone who has a variety of other safer investments. If all they do is sell this type of product, they are most unlikely to be able to form a balanced view of your financial needs. They may be getting commissions for selling you this scheme. Pressure sales tactics are a big danger sign.