Excuse me, but why are you giving advice on information you know nothing about? I understand you have all the right to voice your opinion. If you like Aspen shavings, then say you like it and why you like it. But do not base it on heresay and totally inaccurate heresay. Surely you must understand the people asking these questions are looking for "experienced" opinions, not opinions from someone with no more experience then themselves. You admitted you were basing your opinion of questionable information. So again, why pass on that same inaccurate information?
The reality is, pine shavings have been successfully used for decades and decades. I have successfully used it for over 40 years. It does not cause RI. Really poor husbandry causes RI. Not anything to do with the shavings, such things as poor temps, combined with wet and dirty substrate(any kind)can cause your snake/s to compromise their immune systems, thus getting RI or mouthrot.(stress induced maladies)
Again in reality. If someone chooses wood shavings, either aspen or pine is good. There are more differences between different grades of each, then each is to eachother.
That is, both come is small chips to large chips or strands(aspen) The use of these is based on your particular need. Large snakes, small snakes, deep substrate, shallow substrate. Its more important to understand the use. Or what additives have been added. These products can have artificial scents added to please PEOPLE. Which in turn sells the product.
Lastly, access is important, If a person has a hard time finding one or the other, then simply use the one you can find easily. Particularly if it effects how often you replace it. If one is hard to get and you end up not changing it out when needed, then get whats easy to find.
So in my opinion, its more important to understand the use of a substrate and the ability to purchase it easily then If aspen is perferred over pine shavings. If you polled any number of people, you will find keepers that perfer one or the other or keepers like me, both. Cheers