I would really try and figure out what your outdoor-location to studio lighting ratio is.
I don't consider the Quadra and 600RX in the same light catogory. A 600RX and Ranger RX Speed AS would be a better comparison.
The Ranger RX Speed AS has has lighter flash heads and 8.5 Stops of power control to the 6 Stops of the 600RX. It's modeling light is marginally useful, but you can't use a modeling light outdoors really anyway.
Have you considered the BXRi500? I just picked up a used one from one of the forum members. It's a great light and it along with a couple of Dlite4s are my studio lights that I can augment with a couple of my Ranger RX Speed ASs if needed.
I really like the Power band on the Rangers, it's nice to be able drop way down.
There are plenty of people that are using Elinchrom monolights with batteries, so you'll get good feed back here.
The Quadra looks really nice for a good portable light that is lighter, by far than the Ranger RX Speed AS, but it's not as robust.