Sorry by closed loop do you mean a closed system like the corsair All-in-ones? Because technically all water cooling should be a closed loop, or a pump failure is the least of your worries
I have the Corsair H80iGT which offers 120x240mm cooling area, but in a 120x120 package. It's a big thing, but it does the job well. I'd have gone for the H110i GTX, but my case is designed for air cooling, and didnt quite have the radiator space unfortunately.
Before buying any of the corsair coolers - check that it supports the Corsair Link functionality with USB - that way you can monitor the pump, coolant temp, rad temp, cpu temp etc. all from a little piece of software. You can also color-code the RGB LED in the logo to your case colours, plus set up 'events' such as for me - if my CPU or Rad remp goes over 70C, the RGB LED will turn bright red, instead of white. I think you can do the same for the pump Duty, so for oyu if pump duty fell below a % or whatever, you can change the LED color. I think you might be able to make it do more, but i didnt look at it too much.