I like to aim for a pretty immersive and surreal experience, though it depends on my intentions for that particular expedition; if I'm going outdoors or to a museum, I won't take as much. If I'm doing it indoors or in a desert then sure, aim HIGH. My main anxiety with high doses is social situations, which I'm not good with at the best of times.
That said, I have yet to experience a positive 'heavy' trip. Every time I've really pushed the envelope, it's resembled less of a trip and more of a brain damage simulator. The first couple of times this happened (my second and third trips) I believed I'd lost my mind and was never coming back. The next couple of times, that paranoia was still there because the state of mind was SO far out there, yet I managed to more or less reason myself out of it and waited, as calmly as I could, for it to finish.
This has not deterred me from very high doses, though I don't plan to ever take more than three grams of mushrooms again for this reason. Rather I'm approaching future intense trips with exaggerated caution.