I can tell you what happened to ZipZoomFly. They cheated people. They definitely cheated me out a rebate, and I saw numerous posts warning people about this.
The scam went like this: To get the rebate, you had to send in a receipt (or maybe it was invoice). ZZF did not send a receipt or an invoice via email. You had to go to their site to get it. The thing was if you went to your account, then went to order summary, you print out a receipt or invoice. Which ever it was, it was the wrong one for the rebate. You had to go through some labyrinthine process to get the one you actually needed.
If you complained, you were told they would consult the manufacturer. Of course, the problem wasn't with the manufacturer; it was with ZZF. But they simply stopped replying after offering an obviously garbage excuse.
I never did business with them again. A good reputation takes a long time to acquire, but only minutes to lose. So for all the praise published in this forum, they deserved to die. Good riddance, I say.