You probably have to see, or hear, a turbine run away to really appreciate this, but there is something to be said for the simplicity of furling. I'm partial to this method as it doesn't rely on electronics to initiate something, or electrical loading for control. It is not perfect, but it has proven to be very reliable over the years. Personally, I don't think I'd run anything this size or larger without some means of protection.
Flyweight governors seem straight forward, but are harder to get right than most people assume. The Winco "air-brake" approach I suppose could work on something this small, though I dislike 2-bladed rotors.
I like what Frans has done with variable pitch. Pretty impressive really. On an 8' turbine though, it would add considerable complexity, cost and weight I suspect.
I've had quite a bit of experience with tip brakes. The simplest were aluminum, bent and preloaded against the end of the blade. In an over-speed event they 'popped' and bent out to catch wind. Kind of like a parachute behind a drag racer. These were disposable/one shot and had to be replaced. There were hinged designs - pivoting at the leading edge - that relied on a spring latch. The latch mechanisms, however, require regular maintenance to be reliable.
Electrical loading seems simple enough, but what if there's an open in the circuit - a pretty common state of failure in electro-mechanics.
I think they all come down to compromise and trade-offs. Simple is easy. Robust is harder. Combining the two, now that's a true challenge.
~kitestrings