Well I say keep it on, otherwise there's no incentive to avoid a pile up, no-one's out to maliciously screw up anyone else's race after all. I'd seriously recommend practising crash avoidance a bit on the public races, it makes a big difference. If you're in a long race with a lot of cars on a tight course then it pays to hang back on the first couple of corners, take a wide a line and generally get well out of the way of everyone else. If everyone goes piling into the racing line on the first corner at full chat with cold tyres then there's going to be mayhem!
I kept damaging my splitter missing the apex on the left hander after the uphill section and clipping the armco, every time it made the next lap a bit worse and let Jimbob pull that little extra distance, eventually I just had to slow down to prevent any further damage!