So I did this.
I bought a 50cm piece of Bridgesii. T Bridgesii (also E Lageniformis) is a relative of San Pedro. Trip reports online report it as generally more potent than San Pedro. Scientific studies of both show that San Pedro can be a lot weaker or a lot stronger than Bridgesii, depending on genetics, time of year, luck, etc etc. But that bridgesii is more consistent, so you're less likely to get a dud.
I cut it into pieces and boiled it for about 2 hours. Then pour that liquid off, added new water, and cooked for another 2 hours. Repeated the process once more, mashed the stuff around a bit, then threw away the remaining plant material. I reduced the liquid down to a thick syrup, and then to a resin, which is incredibly sticky. Adding sugar to it makes it less sticky, but I think I wasted a good bit of it just because it got stuck to dishes etc.
Anyway, this morning at 9:30, I took about 70% of the resin. I should clarify - I had about 556g of cactus to work with, after removing both ends to grow new plants from. I reduced that 556g to around 10-11g, with some wastage, and then added sugar until it was about 17g. I took 12g of that 17g and the rest is in the freezer. Next time I'll use the freezer earlier, because it stops being sticky. I think the answer is to pour it into wax paper, then put that in the freezer. Then it isn't sticky and you waste less.
Anyway, back to the trip report. About an hour after I took it, I started noticing stuff. The usual stuff you notice at the beginning of a trip - slight body load, mental alterations. It took 2-3 hours for visual distortions to appear. I didn't have any open eye hallucinations, but if I stared at a spot and let my focus drift, objects would appear to be waving or moving of their own accord.
Compared to mushrooms, I'd say that I felt much more keen to get out and go for a walk. Not sedating at all, if anything it will make it more difficult to sleep. I've gone to sleep while tripping on shrooms before, I don't think I could do that on mescaline.
I would have been peaking around 1:30PM, which is exactly when I went for a walk. I felt a little self conscious, but mentally completely lucid, and I could have had a conversation and you would not have noticed. It is kinda nice actually, knowing that you are on some kind of a trip and yet have such a completely clear mind.
I found a nice bench to sit on, and just sat and thought about stuff while basking in the sun for a good hour. It was great. During that time, I reflected on where I am going. Could I have done this without mescaline? Yeah, probably, although for some reason I'm not sure I would have come to the same realisations. Nothing incredibly profound, just like a take stock of your life and where it is going moment.
I did some work in the morning, on personal projects, and I found that I came to one or two realisations that I'm not sure I would have.
Haven't really felt any euphoria, although in general I'd say I've felt good during the trip.
I didn't throw up, although I did experience nausea, and it has been pretty persistent. Like, I'd be hungry but also not really feel like eating anything at the same time.
Major downsides for me are the body load and the duration. First, the body load. I think what I mean here is that it makes my skin a lot more sensitive. Consequently, I can't decide if I'm too hot or too cold. I tend to feel comfortable sitting down or lying down, if I'm correctly clothed. I kinda don't like the sensation.
Duration - it is 12 hours later now, and I'm mentally back to normal but my skin still feels tingly. That is one thing I like about mushrooms - you have your fun and then its gone and you can get back to normal.
The interesting thing is that I think both have their uses. I still want to do another mescaline trip with a higher dosage. Eating the full amount rather than the 70% that I ate. I think I did underdose a little this time, but not badly. Good first time dose maybe.
But I think mescaline might be at its best, for me anyway, microdosed. Especially with my work as a programmer being part logical and part creative, I think taking this stuff in a microdose form (1/10th or less what I had today) could be amazing.
Mushrooms are way more introspective. When I take mushrooms, I tend to journey deep into inner worlds. Mescaline, at least the dose I took, was the opposite. I thought of myself in relation to other things - my journey mostly.