The BMW 1150 (I-ABS system) & the early 1200 (again I-ABS) system did need a very special rear brake pedal adjustment procedure & a specific up-stop clearance adjustment as the brake switch leaf was operated by the pedal against the up-stop.
Later 1200RT's with I-ABS gen ii were not nearly as picky about pedal adjustment as they didn't use a dedicated up-stop & don't have a brake light switch mounted at the pedal.
That sounds reasonable, since iABS2 no longer needs the switch to activate the servo motor. I've only worked on my '06 RT's iABS, so I'm looking through the DVD for clues on later bikes. Could the switch have been dropped beginning with the Camhead? I'm still seeing it in the parts fiche and RepROM procedures up to 2009.
No matter. My concern was that Rex's experiments might cause a problem with the piston rod adjustment, if it is adjustable at all on the RTW (and not documented on the DVD).
Surely somebody has attempted to adjust the pedal on a Wethead? It's been out for four years now!
The external brake switches were dropped on the 2007 & up 1200 bikes. That is when the braking system switched to the I-ABS gen 2 system. The pre 2007 I-ABS (wizzy) system used external brake pedal & lever switches to trigger the servos, brake lights, & drop cruise control set. The later braking systems (2007 up) used internal pressure sensors to trigger the brake lights & rear servo.
The reason that the rear brake switch being present is very important to brake pedal adjustment is that it includes an external pedal up-stop adjustment. That external brake pedal up-stop position MUST MATCH the rear master cylinder internal piston stop or the cylinder take-up port could remain covered by the piston & prevent full rear brake pressure release. (so on the pre I-ABS gen 2 systems it is very difficult to move the brake pedal position (angle) without causing rear braking issues)
On the later (2007 & up) systems without the external brake switches the pedal adjustment is much easier as there is no external pedal up-stop, so (within reason) a simple clevis adjustment can change the pedal angle/pedal position.
Added: In my BMW parts book it does sort-of show the rear switch for all but if you look closely there is a qualifier at the bottom stating--- "This is a rear brake switch for vehicles with integral ABS".