just to add data, I will confirm that the teflon core retains flavor for longer, and provides a more pure flavor overall. but the glass core really cooks... noticeably more aggressive extraction with subjectively stronger (IMO) effects. you can finish a load in only a few draws with the glass unit, if you've got the lungs. It's not outdone by the S3 or the Evo in terms of raw performance. so, if I was forced to choose, I'd choose glass. but you win either way.
I do miss the old teflon units. the new ones are better overall but I don't think they taste as good, which is crazy because I think the current teflon unit tastes fantastic.
@lazylathe you lucky if yours is still truckin. I went through a few of those units
to the noobs in here, I cannot recommend the delrin adapter enough. takes out all the hassle