Well, considering that that scrape (which was actually caused by my shin bashing straight into the tree with almost no scraping involved) was really just an annoyance, I don't think that particular piece is on my priorities list. I think the next step in terms of safety gear would probably be something like a chest protector. I'm really not all that concerned about preventing scrapes and bruises, I just want to be able to stay alive if something truly gnarly happens. I've also had flying rocks hit my knees often enough (from people doing exactly what you did, by the way) that some knee pads would be good. But of course, the best thing is to just pay attention and hold on tight as a bug's ass when things get rough. 90% of the injuries I've had have been caused by either riding beyond my ability or not paying attention, with the other 10% coming from terrain (there was a real sandy spot this one time...)