RoyalOak's statement is proved by the fact that police pursuit drivers regularly drive at speeds of 100mph+ when chasing, yet it is safer that you or I doing it (which would then be inappropriate speed) as they are highly trained.
Not as well trained as they used to be, sadly. The police have an incredibly bad record on accidents, although that may have improved after new rules were introduced on when a police car can go into 'pursuit mode'.
Unfortunately this now means the police will back off from many chases. Helicopters are far more valuable, but it's not as if every force has loads of these to call upon - and they also cost a small fortune.
But, I certainly agree about inappropriate speed. Some of the safest roads I've ever driven on are German autobahns, where you can have people mixing at 150mph and 50mph without incident.
Here, I'd say the variance in speed is a dangerous one because people would pull out in front of a car doing 150mph when doing 50mph 'because they indicated'. However, the problem is more down to the motorist going slower than the one going faster in this case - but then that sounds like you're saying speeding is safer and you'll be shot to pieces.
I guess most people know what I mean though - especially if they drive a lot and can observe all these things first hand.