My son went to Proctor for his jr and sr years. What I especially liked about the advisory system is that you are free to choose your advisor after your freshman year (not sure about the exact timing, but I know that Proctor initially matches kids with advisors who (hopefully), have something in common with each other. But you are free to change advisors if there is someone who really resonates with you.
The program worked well for my son. We heard from his advisor infrequently, but that was fine. My son, on the other hand, heard from him often.
Oh, and btw, advisory meetings often revolved around meals at his advisor's home, with the group pitching in on the cooking.
I liked it. At my daughter's school, the way it works is that your advisor has to live on your floor as the dorm resident. That way, I am sure the school reasons, your advisor keeps very close tabs on you and can spot trouble before it happens. But, imo, the down side is that you may change advisors yearly, and it won't necessarily be someone who shares the same specific academic passions that you have.