The crude ECU used a speedometer based speed sensor and an electric idle circuit cut off solenoid in the carb (a spring loaded needle/seat type valve) to cut off fuel flow when vacuum, engine and ground speed were high and the brake lights were on. The same solenoid also acted to prevent run on/dieseling when the ignition was turned off because it was only open when the circuit was energized.
In my car, I believe there are very few situations where I will need to accelerate to get out of dangers. Also being in my car, I'm going slow enough to where I should be able to see 99 percent of what's going down and that's why I do ICE-off coasting.
In a motorcycle, you are almost always the tiniest thing out there. People look for cars, but don't expect bikes. I can see many situations where I might need to speed up all a sudden.
If you're going to commute with it (i.e. put alot of miles on it), I would price out the difference in tires between the Ninja and the Honda. Being a performance bike, the Ninja's tires are probably alot softer and though it doesn't have huge amounts of horsepower to chew up rear tires, you probably would still be replacing a rear every 5-8K miles and a front within 10K. The Hondas aren't going to last forever, but would be a little harder and probably a little cheaper.
As far as fun, there's no comparison, get the Ninja.
have you ridden both bikes ? a test ride would make your decision much easier. as far as being able to accelerate out of a situation, I have been riding for more than 30 years, and I have never had to accelerate out of trouble. learn to work the brakes, and remember that most of your stopping power is in the front brake, always assume the other driver doesn't see you, and be aware of your suroundings. remember also, that gearing on a chain drive bike can be changed relatively easy.
Here's my $0.02: I have heard that Ninja 250's are bikes that are fun to learn on and still remain fun even after your skill has progressed to where you could get a bigger/faster bike. I hear no such thing about the Honda. Long-term, I think you'd be happier on the Ninja, and I think the fuel economy will be a lot closer between the two than those articles stated. Advantage Ninja.
'67 Mustang - out of commission after an accident
'00 Echo - DD
'11 Kia Rio - Wife's DD
'09 Harley Nightster - 48mpg and 1/4 miles in the 12's