As many have said, this has been hashed and rehashed over again. The debate won't die, except the results... that is when students see a wicked awesome robot built by mentors - it doth not inspire nor encourage.
There are Mentoring guidelines. I like section 8 a lot:
http://www.usfirst.org/uploadedFiles...ng%20Guide.pdf
I Do, You Watch
I Do, You Help
You Do, I Help
You Do, I Watch
I come from a world of FLL, which is still FIRST. In FLL, students do *all* of the work - emphasis mine. Mentors and Coaches encourage and provide the process; keep everything including sanity in check. In FRC, we encourage the engineering process, learn the technical knowledge, and at some point, we as mentors do need to start turning the keys over to the students - as much as they can manage. The idea behind FIRST isn't just to inspire, it is to build leaders... They can't learn to be leaders having to take the backseat the entire time.