Personal anecdote. Just found out about 1x to 16x risers and found out they were all sold out on most sites. So I went to ebay to find ridiculous prices and like a month shipping from China. I almost got caught up and bought one. Glad I didn't, just looked at my motherboard to find my 7850 completely covers the 1x slot.
I guess moral of the story; dont jump on bandwagons, and know your hardware.
You can still run a riser out from underneath the 1st card. It won't allow for as much separation but it still works.