No more or less dangerous than the backup created due to a highway full of "looky-loos" gawking over a cop having pulled over someone for doing 10 mph over the speed limit along with everyone else.
I wonder how many people have rubbernecked at a person pulled over for speeding, only to rear-end the person in front of them because they weren't paying attention. Probably more than PDs would ever admit. Oh, but that's okay - they want to back up traffic (and forget about the hazard created by having everyone distracted and slamming on their brakes and backing up traffic for five miles) - it's about "increasing police presence". That's more important.
Don't get me wrong - there's an appropriate time and place. Some jackass whipping in and out of lanes, riding two feet off peoples' bumpers and intimidating them with aggressive use of their headlights in their oversized, poor-handling, illegally modified "boy toy"? Damn straight they should get a ticket. Perhaps several. Someone driving drunk? Ticket. Wrong way down a one-way street? Most likely a ticket (or at least an inquiry into what the heck they're thinking). Running a stop sign or a red light? Ticket (unless there are BIGTIME extenuating circumstances). Accident? Ticket pretty much by default.
Just because some city bureaucrats have decided to put a sign on a strip of asphalt saying "35" or whatever doesn't change the de facto reality that if everyone and their brother can drive down that road for years at 70+ without a problem, that the speed limit is stupid, moot, irrelevant and probably a mistake.
Perhaps I (and others) would have a bit more respect for government, police officers, traffic laws and authority in general if it weren't so blatantly manipulated in the interest of insurance company interests and dollars, day after day after day after day after day. We all see it daily - a uniformed guy (or woman) who has dedicated their lives to public service and puts their lives on the line for the citizens they supposedly represent (whom we SHOULD be able to respect and thank for their service) forced into the role of tax collectors for dollar-drunk government do-nothing bureaucrats. That's a tragedy.
Speed is FAR less dangerous than differences in speed (as has been said). It'd be nice if on a three lane road, the speed limit was (for example) 40 in the right lane, 60 in the middle and 80 in the left. Or something to that effect. Of course, ideas like this will never fly, because we need to continue to dumb down our system for a society increasingly populated by stupider and stupider individuals with less cognition skill, less language skill, less analytical skill, etc. It'd be "too complex" for some retard illegal alien to make sense of, so it would never be considered.
Welcome to Amerika. Land of "the free".