The only information I can give you on this topic is personal accounts. My friend likes to pick up a lot of bud at once, so his room tends to reak. His mother, unhappy with this, decides to raid his room one day. When he gets home, she asks him, what the fuck is on this and why does it smell so good ? Apparently, according to her, the weed has gotten much more potent. Also, I feel like the bud from the 60's and 70's was mostly regs and today we've evolved into better growing techniques and new strains, which are obviously better than regs since it costs more and (for me at least) gets you way higher.