I've personally driven (in a car) behind cyclists using SFs and Dinotte's. There's a huge difference. The Dinotte is so bright that the cyclist automatically gains a level of respect that's normally accorded only to cars (in addition to being visible at a greater distance). Yes it is somewhat blinding and yes it is somewhat painful to look at--but not any moreso than the LED taillights luxury cars are sporting these days. Personally, I was also a skeptic until I saw this for myself.

Certainly, there's a part of the extra cost that exists as a premium for owning the latest and greatest, but it doesn't mean we're getting cheated. That's the way it's been with consumer electronics for quite some time.
If someone got hit from behind and was using the Dinotte, I would rule out the possibility that the driver was looking at the road straight ahead of the car and still did not see the cyclist. In fact, I would conclude that the driver was probably not looking at the road at all (applying makeup, reaching into the backseat, etc.). With the SF, I would be less confident making these conclusions.
The SF is an excellent light. I think most Dinotte users were at some point SF users. Myself, I still use an SF for leisurely rides on slower roads. But at night on +40mph roads, I break out the Dinotte. I appreciate being able to modulate my response to the level of risk on the road, instead of tying myself inflexibly to one system for all situations. That's the decision I'm comfortable with (As a sidenote, before the Dinotte, I used twin SFs--which I find to be a good compromise for those who won't buy the Dinotte).