I only named breeders who have either discussed on their care sheets or on forums that they use or recommend pine. Again, Barczyk and Spuckler are easy examples.
I live by the East Bay Vivarium and have dealt with Owen and Jon for years. Not only do they almost exclusively use pine (for caging, breeding, etc.) they recommend it even though they sell bulk aspen, bulk cypress, etc.
I could easily name another dozen well-respected people in the hobby who use it but considering the e-taboo on the stuff I'm not going to "out" anyone.
Why would people who make their bread and butter on the successful propagation of snakes use it if it was so damaging long term to their livelihood?
Tin foil hat theories welcome.
In the mean time, chew on this. Aspen (despite uninformed claims to the contrary) also contains phenols, catechols and salicins. What do they use these for? Just like pine - defense against potential predators.
So, has anyone figured out yet what the long term effects of these compounds on snakes is yet?