Metro, that's right where I installed my brake regen button, I love it on the shifter. I'm also considering an FAS button, I'd also mount it on the shifter next to the regen button. I'm also going to heat shrink around mine, only cutting out for the top of the button, so it's more integrated.
I want to be able to FAS at any speed, so I can at EOC the Turtle. You had one of these, did you have FAS in yours?