That B3D link proves you wrong. Did you not look at the post I sited? He said no special io was required to run the demo. If that's the case there is no reason to downgrade the textures to get the demo to run on pc.
Edit:
Here's another post from that B3D thread from Andrew.
"Sure, but there's a difference between "we need/really want an SSD because they are hilariously faster and lower latency than HDDs and optical drives that previous consoles relied on" and "we need tons of bandwidth and lots of fancy stuff on top of that". Don't get me wrong, all the new fancy IO stuff is great and I'm sure will help improve things further in the future across the board in games, but I feel like Epic has been pretty clear from the start that this stuff works well on all of the target platforms and will continue to get better."