I am a firm believer in Shimano's trickle down technology practices...i.e. this years 105 11 speed is last years Ultegra 11 speed which was the year before's Dura Ace 11 speed etc etc........
It doesn't quite work like that. Shimano will lead out with a new concept such as 11-speed or hydraulic brakes or electronics or whatever, by first putting it on Dura Ace or XTR. Then, the next year, a cheaper version of it goes onto Ultegra/XT. What they trickle down isn't the same quality or materials, just the same concept. The trickly-down sometimes uses cheaper material (steel rather than titanium) and almost always, a different design. Often durability is also sacrificed, bushings instead of ball bearings for instance. (But don't take this as an indication of poor debility on lesser graded kit).
There are two major differences, from a riding perspective, between 5800 and 5700, firstly the 5800 gear changing is a little bit lighter, smoother and crisper than the 5700, not a huge difference, but it IS noticable, secondly cut cut cut cut .....and this is the BIG difference......the stopping power of the 5800 brakes is FAR BETTER than the 5700.
This is simply not true. We cannot increase the stopping distance on bikes any more with the current bike design. The limiting factor for the front brake is overturning momentum, not traction or brake force. The limiting factor for the rear brake is weight over the back wheel - the wheel simply skids and once it skids, it does very little braking.
Lets start with the front brake first. You cannot skid a front wheel on a bicycle where there is good traction. I'm not talking ice, I'm talking dry tarmac. It is impossible because the bike does an endo before it can skid. That's the reason motorcyclists can do stoppies. If the wheel could skid, you cannot do a stoppie. To improve the brake distance you will have to redesign the bike so that the centre of gravity is below the level of the hubs like in a car.
Rear wheels do very little of the braking on a bike, perhaps only 15% if the rider is extremely skilled. Note that these limitations have nothing to do with putting on disc brakes, better pads or any such. Once you can do an endo, you cannot improve braking distance.
I chose my words carefully and I never said you cannot improve the braking experience. Better wet weather performance is obviously a good idea. I like smooth actuating brakes etc etc. We would all like to brake using less force or brake easier from the hoods (which is what was improved on the new Shimano equipment BTW).
We would also like better stopping distance but that cannot be had. Unfortunately only the guys on recumbants can dream of that. Bicycle magazines never tell you that. I think they don't even understand it.