I would concur that value ad is typically the way to go, particularly in student rentals. But like Will said, markets can vary.
Students, in my opinion, are actually not much riskier than market-rate renters. There are good and there are bad in both marketplaces. To your second part, the one nice thing about student renters is that even when you have bad ones, they leave eventually. I have always liked knowing that there is inherent resolution (them moving out) to most issues.
Turnover can very from market-to-market. Some schools allow students to live off campus all 4 (or more) years. This would give you an opportunity to rent to the same person(s) for a few years. Some schools only allow upperclassmen to live off campus. In this case, you could expect to turn 50% of your units on any given year. As nice as it can be to have stable tenants, we usually feel like the unit(s) need to be extensively turned over if the residents are there 3 or more years. So one could argue "lighter" turns are easier every year or two, versus, extensive turns after a few years.
- How risky are student tenants? We were pretty good kids in college, but of course we had parties and made our share of messes. I can handle some college shenanigans, but I'd also love to hear some horror stories if anyone has one.
- What sort of turnover can we expect? The idea of a natural turnover seems more of a benefit than a drawback to me, but I'd love to know some rules of thumb for just how frequent can be expected.