Would be a nice idea, but flawed.

Illegal in some states, anything electronic on the bow sights.
Multi pin sights, which do you use?
How would you trigger it to range..or does it constantly range things 24/7?


Fanciful idea, just not very practical right now.

GMMAT, the branch theory is moot, there could be a branch inbetween your handheld rangefinder and a deer just the same as your sights and a deer.


EDITED: posted at same time, saw your answers...multi buttons gets too complex, still doesnt eliminate the fact it would be illegal in alot of states.