Amen, Don.

Even though I've begun to "refer" to cheatsheets ~ something I would never have even imagined years ago ~ I feel most confident when I know I can glance at something for reference. I certainly don't fix my eyes upon a lyric sheet and read every single word.

And you're right about the necessity for really understanding a song in order to "know" it and therefore to present it adequately. There are songs I've known for decades that I understand quite deeply, but whose lengthy texts provide me with plenty of opportunities to "draw a blank," or at least to hesititate long enough to lose the beat and ruin the musical setting for the words. Better to work with a safety net, as long as I feel the need.