Interesting. I remember an ayahuasca session provider in London telling me that LSD and other chemicals can scare the ayahuasca spirits away. It certainly took myself and my friend more ayahuasca than the rest to get there, and we are both experienced with LSD and continue to use it on occasion, and it was definitely a potent brew.
Interesting your experience with these tabs, I have only found them consistently to be incredibly clean and smooth, while being very powerful at the same time. I wonder if there are different batches of these floating about, or whether there is differences in body chemistry at play. I used to be highly sceptical of the 'clean acid' idea, in that if its LSD, it's LSD, and a few impurities won't really any difference to the experience, as they will be present in such miniscule quantities in a standard dose or two of LSD. But having shared experiences with a friend, I have come to a different conclusion. I remember being on a good dose with a friend at a festival, he got sick and vomitied several times, and I got really quite severe stomach cramps for a time, wasn't pleasant or a placebo effect that's for damn sure. So I think purity, as well as potency, may be important on consumption.