Thanks for the replies everyone.

As for why I didn't close my eyes - literally the only thing I could do was hang on for what felt like dear life, any thoughts of doing anything went straight out the window!  Pretty sure I broke through...

I think the setting had a lot to do with things.  If I wasn't so worried that my neighbours could see me travelling at hyperspace, and had that coldish experience the night before things would have been much better.  Maybe it was telling me I overdid it the night before ("Aren't three miracles enough in one day?!" ) and wanted to show me how powerful it really was, who knows?  Certainly taught me respect, that's for certain.  I've been working my way up the dosages again, and the positive vibes are back, so that's good.  I still want to go exploring!  I would love to see "the other" better than  just some mild CEVs in a dark room.

Maybe it was probing to see where my limits were so that i'm not as worried about going that deep again, I did feel like I was proper "at the edge" at the time.  Maybe it's like one of those old so-called Chinese proverbs - "He who has been hit on the head with an axe positively enjoys being hit on the head with a wooden cudgel."

The aftereffects have been great though, I feel proper refreshed and alive again.  Think i'll try again at the weekend.