The 'need' question is tricky with safety equipment: most of the time you don't need it at all but when you do need it, even if just for a few seconds, then you need it quite badly.
I happily rode the reds and blues at BPW with my normal XC riding kit, I don't recall seeing anybody stormtrooper-ed up.
There is plenty of opportunity on the reds and blues to have an almighty fast stack (especially on the blues higher up, I seem to recall, which were pretty fast) with potentially nasty consequences.
But nothing is committing, it's all up to you.
Ride within your limits, don't go full-on, you should be OK.