I use the same risers with rx 480 / 470 over 1 year. You can use then without problem.
No, you haven't. RX480 came out June 29th 2016 and RX470 in July 2016.
everyone is gonna cry that don't use molex as far as i am concerned I have never had one melt down as long as you keep max of 2 per PSU cable connection
The only RX480 that would be a problem on Molex is the original reference RX480, and even then that should be fine with since AMD fixed the PCI-e clot power issue with a driver release. Yes, 2 GPUs per Molex chain is acceptable. I'd keep it to 1 GPU per chain with a RX480 reference card.