I would think not at 80 grams, at least *I* would not be comfortable trying it. I've been in public areas as busy as supermarkets, but it was on a fairly low dose--the experience was overwhelming in a fun way, I felt like "to hell with it, whatever happens happens", and I was able to perform simple interactions like paying for some fruit and cigarettes.

To be honest with you, I haven't experimented with doses higher than 35 yet. I like to conserve it as much as possible, and I get the effects I want from 20-30 g. Have you tried a dose that high before? If we're talking your first trip, or your first trip in a place that crowded, I would go with a lower dose (depends on the particular batch of cactus of course). Either way I'd think the experience would be more enjoyable in a different setting, but that's just my personal taste I guess.

For the nausea I would recommend smoking some pot 20-30 minutes after ingestion, either after throwing up (if you have to), or after it begins to get too uncomfortable. How bad it gets probably goes up with the dosage, but again I don't have enough personal experience to say whether there is a huge difference between 80 and 30, in terms of stomache discomfort. How long it lasts? I'm not sure how long if you just ride it out, for me it stopped almost immediately after smoking, so maybe it just depends on when you smoke. It really helps a lot as a natural medicine, and helps kick the trip up another notch... you'll be in outer space afterwards

My only other idea for that is to have an empty stomache before ingesting... even if you're hungry, just wait a while after the experience is underway. After the nausea is gone it should be fine to eat (food can be pretty interesting and delicious), but you're more likely to throw up and/or experience discomfort on a full stomache.