At one point, I'd read every ST novel available - no longer true. I've mostly lost interest.
Ditto. I still have about 100 or so, and I reread many. Mostly published 10 years or more ago -- most of the newer ones just don't excite me (and the ones that do, I have).
And while I read about as fast as DSD (I think it was just about 13 hours on the latest HP for me as well, maybe an hour or so more or less), I don't think I'd want to read any faster. I know I miss some details (and go back and re-read 'em) at my speed.
Well, except for textbooks and the like. I read (or really, skim) those considerably faster. Then again, those are not exactly known for nuance and poetic language.