Unless they’ve changed a lot, no probs (I rode the world cup the first time in an open face, it’s fine as long as you’re ugly). The red is, slightly insanely, pitched as an “XC red”
OTOH, I’m pretty sure they hire out helmets at the bike shop and it wouldn’t be a bad idea at all even for the red. You can do a lot of runs so that breeds speed and possibly a little bit of contempt, and because it’s so rocky and has a fair amount of height drop in places, it’s all relatively high consequence. I’d be equally happy in either hat- I tend to wear a fullface purely because I never really know what track I’m going to do til I get to the top