I won't ever fuck with LSD because of it's possible schizophrenia triggering side-effects, but I did spend a good portion of my FI listening mildly high on weed. Although, 100% of Tool albums are improved by being high on THC. I don't think FI will ever reach Lateralus (too much nostalgia attached) levels for me, but I definitely rate it higher than Undertow and it might even be better than 10,000 Days for me.
I really hated how understated Maynard's vocals were on initial listens to FI, but now I've really come to appreciate how heavily featured the instrumentals are. It really allows you to better appreciate the goddamn insane level of talent Carrey has. Invincible might be a top 3 or 4 Tool song for me.