Yes, I agree for the Touratech mount is nice, and I have one mounted on another bike. However, because the wiring configuration for the Zumo 660, you aren't really "hot swapping" the Touratech with multiple bikes easily.
So here's what I ended up doing:
Here are the parts sourced from Lowes:
The Hillman Group Spiral Wrist Band - Plastic Key Rings Item #: 33287 | Model #: 701304
Gardner Bender 10-Piece 1" X 1" Black Mounting Pads Item #: 292685 | Model #: 45-1MBUVL
From auto parts store:
3M™ VHB™ Tape 4910 Clear (It comes with foam tape, but I have really good luck with this stuff)
I hang the wrist band off the mirror mount. Works with both mounts I have including touratech locking mount and the stocker Garmin mount.