Thanks for all the comments, Folks- I appreciate it. (I know some of you are on Bentrider as well !)
Yes, I'm clipping in with Nashbar Ragster sandals. I'm aware of the leg suck phenom... and having had a knee replaced a couple of years ago, the thought of a leg going under the trike is terrifying! As a matter of fact, just after unpacking the trike, I hopped on it to just go down to the corner after an initial visual checkout- to see how it felt- and my foot popped off the pedal before I got to the corner, and FORTUNATELY, my heel bounced up off the pavement, instead of going under. Believe me, it was a wake-up call of the first magnitude. I will never, EVER be unclipped on my trike again. Never.
We equipped my wife's T/T Rambler with PowerGrips as well... we ordered it with them.