When I changed routers to a AirPort Extreme 5th Generation, I see no difference in terms of speed, from Safari or Mercury and Dolphin also, Or it could be iOS 7.1 that picked up the speed improvement of Safari.
I use iCab mobile although its less iOS7 than it could be an update is promised. I've tried Mercury Browser but the adblock isn't as effective as iCab and it doesn't integrate with Launch Center.