I have coached both as a high school student and college mentor. After seeing a bit of both sides of the coin, I think it's pretty safe to say that it's about what works best for your team, and what will give you the best chemistry and results. Different drivers and individuals react to different coaches and individuals better than others, and it all depends on what will fit for your team. There isn't a "right" or a "wrong" way to do it.
As I've said in plenty of other threads, chemistry is a big part of the picture. You have to know what individuals can fulfill the job and work together (and with other teams) properly.
I had the absolute pleasure of working in, what was in my opinion, one of the finest drive teams in FIRST in 2006 and 2007. I had known the driver since 7th grade, and he and the operator were best friends since elementary school. We worked together fluidly and easily, and our chemistry enabled us to perform much better than we should have given our robots. Our attitudes and skill sets complimented each-other, and it resulted a well-oiled, adept drive team.
This year, I was the understudy to an outstanding collegiate coach, Mike Williams of 1712. I also coached our "2nd drive team" who operated roughly half of our qualification matches (since the entire 1st drive crew, including Mike, was due to graduate). I know for a fact, I was nowhere near as good of a coach this year as I was last, at least partially because I didn't quite have the same level of chemistry and comfort as I did with my previous drive teams. This was especially true when I filled in for Mike on the 1st team, as he was
much more skilled at communicating with that driver than I. That was his team, not mine, and for good reason. I'm glad I had this experience, especially at building chemistry with the future drivers of 1712, and I hope I get the opportunity to continue coaching them in the future.
I have coached with and against many of those mentioned in this thread, as well as many other great and not-so-great coaches. I've learned a lot from working with many, both positive and negative. Some mentors have shut out my ideas, but that is a vast minority. On more than one occasion I gleaned some strategic insight during both the pre-match planning and listening to them coach during the match. I have seen some tremendous students coaches, and some who speak maybe two words the entire match. I have seen adult coaches grab their students my the shoulders and yell at them, and I have seen students cuss out their drivers. I have seen both students and mentors execute strategies I've only dreamed of to perfection.
As for the suggestion that students are every bit as prepared to handle the pressure and full scale of coaching, I know for a fact that isn't always true. There are many who are capable, but the maturity and experience needed are often much easier to find in adults (although some of them are lacking in it as well). I have also encountered a handful of coaches who don't have the same level of respect for student coaches, and often don't respect their opinion as much as they would if it were coming from the mouth of another mentor.
I know for a fact that I have room to improve, and my problems also didn't magically vanish when I transitioned to a college coach. Though the problems with pressure and the situation aren't as overt as you might imagine (it's not like anyone is suggesting that student coaches will break down and cry), they do exist. I have yet to have much success in the elimination rounds, and while some of the reasons why I have lost may be out of my hands, I can guarantee I am at least part of the problem. I have room to improve and grow as a coach, and I look forward to doing so.
Also note, that as a student coach, I did have a fair bit of success. I was one penalty away from reaching the Galileo division finals last year. Against 1114 I am 2-0 career (I'm not sure if it was Karthik or Derek coaching at IRI 2006, but it was Karthik in 07). Against JVN I am 1-0 (not counting matches where my robot wasn't on the field). Against Paul Copioli I am 2-0*. I'm 2-1 against Andy Baker.
Sorry for rambling, I hope what I just said makes any sense. Bottom line, do what works for you.
*Although I'm 2-0 against 217 when Paul coaches, I'm 0-2 against them when he doesn't....hmmm.... 