"Maybe a switch in prefs where power users can switch on some extras"

In my experience, this is usually a downward spiral. Basically think of a switch as doubling the testing workload and adding to maintenance overhead. That's how you have to weigh every checkbox you add to an app. It can get deadly pretty quick.

The best idea is to design the UI so that it works for everyone. Maybe the power users aren't 100% satisfied but if they can get to an 80% happiness level with it, that's enough.