Vocabulary.
I have approximately 9 years of post high school education, and can read with comprehension at a fairly high level. However, my daily vocabulary is not that broad. It's difficult for me to recall unfamiliar words on the fly. When I listen to podcasters, I'm always surprised by their verbal depth and breadth.
Is this your experience as well?
I do feel like I have a pretty broad vocabulary base, but I do relate to your difficulty to remember words on the fly. Way too often I have the right word on the tip of my tongue, but just can't remember it. I know this isn't specific to SDAM, but I feel like it happens to me way more than to most people. I'm often searching up synonyms on google and in thesauruses to get what I want to say out right.