The good thing about breeding with wild or feral populations is these may have adapted certain resistance through natural selection. In the Americas cannabis was introduced less than 500 years ago. At least the hemp type. I don't know if the locals bred the hemp to get today's Columbian, or if a more psychoactive variety was introduced later. The problem with strains bred to be true to type, and hybrids made from these, is one tends to loose some genes from the pool that might be desired for breeding programs later. So I think starting with a land race would be good. Either to select good phenos to stabilize for making hybrids, or to select individuals from the first seed crop to cross with elite strains, take the F2's, cross with each other, then select what is desired from the F3's, etc. etc. Or would you find a great male and cross to F2 then back cross to the mom? Some seeds should be left uncrossed, but selectively bred outdoors from the first seed crop in order to eventually create a nicely adapted variety for my climate. I'm new to this, so I hope I spoke correctly. Mostly I've read a basic book on vegetable plant breeding. So if cannabis is an out-crosser there are perhaps some undesirable recessive traits one can encounter when trying to stabilize a line?