Thanks for your reply, jrraines!
Also, only now, after looking in more detail at DigitalWriteFast (I also hadn't seen the excellent and concise description at Google Code Archive - Long-term storage for Google Code Project Hosting. yet), I understand how foolish my question was. DigitalWriteFast requires pin numbers to be known at compile time. Period.
i.e. digitalWrite(9, HIGH) can be sped up, digitalWrite(i, HIGH) can't.
Likely this will be obvious right away to most readers of this topic, but to me, as a novice, it wasn't.
Thanks for your time! 