Yes, I once groveled on my knees ("I love you, thank you guys!" ) when surrounded by 30 foot furious ROARING lion-like entities, furious because I had used it disrespectfully... too much alcohol in the blood, too impulsive, no preparation. Big mistake, good lesson.
Another time, I specifically asked 'them' to get to the bottom of all this. No more chickening out! Be careful what you ask for, you might just get it... Things got thousands of times more intense than ever experienced before, terrifying because of the sheer power - a new level. Nothing to do with dosage. I admit fear crept in because of the enormity of it, it's quite something to handle.
But hey I survived intact, one may be forced to re-adjust ideas about life and the universe but that doesn't count as harm, does it?
So, no reason to back off: next time, it was just the opposite: pure bliss, this time it felt thousands of times better than anything felt before in life! That was in august 2008 and I haven't broken through since, still digesting and waiting for the right moment.
Fear is understandable, but fear of fear is just silly! Don't worry about fear, just be careful, prepare well and take it very seriously but at the same time don't worry about it. And put the lessons learnt to practice (the most difficult part).
Good tip about the mushrooms by the way, I second that!