Yup that was me last year, though someone else did it the year before on the first long descent (Bailley Bridge) resulting in ligament damage. As Surfr says – no long term damage, just a good 5″ scar. I now ride in the Dyfi with 661 Kyle Straits, but that is more to appease the missus as she has been more affected by the accident than I was. If I rode up there without them and came off hurting my knee again I’m sure she would be jumping up and down on my bike so that I couldn’t ride it again :o(.
It is entirely up to you – I fully agree with Ambroses’ statement and now wear knee pads anywhere it is rocky so that I don’t feel the need to slow down.