bt

BR-5700 or BR-6600?

if one set is better, how much better?

I'm kinda stuck with one set and wonder if I should buy the other model to get better braking?

redlude97

6600, modulation will be all off with 5700

bobonker

6600 + Swissstop green pads will do the job very nicely.

Bob

revchuck 

If there's nothing wrong with whatever you're using, changing up would be fixing something that ain't broke. If you just want to change something for the sake of changing it, keeping the brakes you're using and switching out the pads is easier and cheaper. If you get the Koolstop salmon pads or the Swiss Stop green ones, you might get an improvement over the stock pads and will gain a couple of style points.

I've used my 6600 shifters with 6600 brakes and TRP r920s. Both worked fine. The 5700 brakes would probably work fine too, but I haven't tried them.

justkeepedaling

6600, it just plain works and works well.

bt

would the 5700's work better with [h=1]Ultegra Di2 ST-6770?[/h]

ThinLine

Shimano Dura-Ace brakes of the 7900 variety, best brakes in the world. SRAM Force close second.