Sliding tires displace dirt. This is not good for your trails. You might displace less with a "cuttie" only because your tire is sliding less, but less bad does not equal good. [Not implying that I can ride fast without occasionally displacing some dirt, just encouraging awareness. Got to be nice to your trails.]cutties dont hurt anything from my understanding
And helmets? You don't need one until you need one. Plus neurological damage is like so not hot right now. This is one place where even though the probability of catastrophe is not necessarily enormous, the consequences are unacceptably high.