A version of the lecturer review website Rate Your Lecturer recently became active in the UK.
Do you know of any studies which consider to what extent students use this or any other review websites to guide their choice of university?
This is necessarily incomplete, but I do recall a few studies on the correlation between ratemyprofessor.com rankings and student evaluations. Two such studies are:
These are disappointingly old though (2006/2007)
There's a more recent study from 2011:
As for other studies, your google is as good as mine :)
Not confirmed by genuine research, but a very strong hunch based on some decades experience: I'd anticipate that having a few crank-negative reviews among mostly-positive is tremendously beneficial, for more than one reason. First, your "supervisors" (dept head, dean, etc) are often not so naive as to think that there'd be no complaints, so it's harmless. Even better, and more significantly for your day-to-day life, the rants of a few cranks may significantly inhibit other cranks from signing up for your courses. "For the wrong reasons", but to your benefit, etc.
This would apply currently to top-50-research-schools in the U.S., I think, and I'd imagine to most other places in the U.S., since most have not committed to any quasi-automated officially validated anonymous rating system, or any other rating system for faculty teaching.