Is all HYIP scam?
As I was scammed several times 6k-finance, Eurtrade if only to mention some, I learned fast to recognize the real thing. At the moment some of HYIP which looks quite serious aren't very promising.
A3Union for example looks professional. But they support simply doesn't work. I withdraw my deposit as soon as it was possible.
Of course on other side, I have very positive experiences.