The Mr. Nice seedbank
http://www.mrnice.nl/dhtml/strains.php
are breeding high CBD strains that are specifically for medical purposes, to improve the overall medicinal benefits.
The 'old' vs. 'new' weed argument is really just a testament to the selective breeding process, as almost all of the super potent strains around today are hybridized between the two subtypes, cannabis indica and cannabis sativa. Modern taxonomy implies that indica is actually a type which evolved from sativa, as seeds found their way to northern latitudes via animals and humans.
When I started smoking in the mid 70's, all the rage was brick red Columbian, which was pure landrace sativa. Throughout the 80's and 90's the importers began using Mexico as their main source, and at first the old cycle of feast/famine predominated, since most Mexican strains had derived from Panama/Columbia landrace sativas;ie; pure strains which had evolved in that particular climate for thousands of years with minimal interference.
The sativas were powerful, but as the 80's progressed, I noticed two things;
1) the feast/famine cycle stopped, there was weed from mexico year round
2) it was indica
I finally realized they were growing the indicas through the winter short season, since indica will produce hard dense flowers in Mexico in the winter.
Most people who consider themselves aficianados likemental aspect of the high that is lacking in the indicas.
It is stronger now, but it was strong then.
(MV- THC and actives are actually 'phenolic' in nature, not alkaloidal, as the contain no Nitrogen-Carbon linkaages. I am aware that there are some very minor alkaloidal components, the predominant ones are terpenes and sesquiterpenes and around 30 or so different phenolic cmpds)