Really looking forward to giving this a go! Some cactus will be on its way shortly.
An interesting little side note regarding cactus potency...I think freakishly potent batches of cactus may well exist. I met and and talked to an interesting character from Oz at Boom festival in Portugal last summer who I'm still in touch with now. He claims to be the original inventor of changa, and he introduced me to it (was an amazing batch as well).
Well he also had on his person some very potent cactus that originated in Peru that he got off a shaman while there. I was unable to personally bioassay this batch due to lack of funds, and had to choose this or changa, and went with changa. He claimed that 5g of dried cactus flakes was a psychedelic dose, with 2g providing a nice buzz. But people remember that being plants, concentrations of alkaloids are subject to wide variation...just because Erowid's 'facts' don't comply with other people's observations, don't make those people wrong! He also claimed that the cactus was very old, and its activity was almost certainly due to alkaloids other than mescaline. I trust his observations, and he hasn't led me astray since then...I'll drop him a line and ask for more info, was a while ago now.
Actually though come to think of it, it might be more logical to assume that what was being offered (didn't get a good look a it, just a tiny taste) was a natural extract produced via a method like this one...