Money. Money. And more money.
SFI stands for Strong Future International. Based on what I have read all the stuff, I came to realize that it's a bit tedious and a little expensive just to make a dollar. SFI requires to purchase a product from one of their affiliates in order to keep ball rolling. If I am not mistaken you need buy an item worth $30. That is a lot of money to cash out to begin with.
One time or the other I thought SFI Affiliate Center is just another form of pyramiding. Not to mention the referral schemes SFI provided to you. It may seemed simple and less work required but instead of giving you dollars instantly, SFI is giving out points (not sure if it can be redeemed as cash) and coupons. I dug and read forums about the coupons they're giving out, someone said that he had coupons with the names of the restaurants on it but could not use it because the restaurants did not exist. But I can not just snap-judge SFI that it is a scam because I have not experience that just yet.
I am thinking I might be good, contented with Google's adsense if that's the case. Although, it may take some time to earn your money out of Google ads but at least you did not have to invest much in order to gain more. Time is what adsense is all about. I can wait. ;)