Wear does not seem to be a problem so far in our testing. Sure, the build plate will wear out sometime, but you should be able to do a lot of printing before needing to replace the build plate. And, as you say, it is easily replaceable (and being injection molded, should be fairly inexpensive).

Regarding homing sensors, we're working on a novel approach to that. We'll be announcing those details in the Indiegogo launch on 5/28. (Soon!)