Man of Honour
So if you had the 360 with a CPU and GPU (or two) in the loop, would you never need to drain it? That's a big bonus over a regular loop, and at a significant saving from a company you know are producing quality components. What's the catch, seems like a great product to me?
I wouldn't use just a 360 for a pair of gpu's and the cpu. I would want at least another 120/140mm rad for that.
Regarding draining it, If you used full cover blocks and changed gpu's then you would need to drain the system but if you kept the same cards with the same blocks or used universal blocks you wouldn't need to drain it unless you had a component failure (I have never had a water cooling component fail). When I first started watercooling I decided to always use universal gpu blocks as they can be used over and over again. This meant that my first loop went through several cpu and gpu upgrades over 2.5-3 years and was never drained once. It was a mix of de-ionised water from Asda and an additive that I can't remember the name of from back then (not water wetter, the other one everybody was using back then). I did a similar period of not draining up to a couple of years ago using de-ionised water from Asda and Primochill Liquid Utopia (no longer available ). Both of the long periods of not draining had no problems. No loss of performance, no gunk build up and most importantly no leaks. With the right liquid/additive I see no reason why any watercooling loop couldn't run for equally long periods.
So what would one need to makes this also cool two GPU's? Backing plates for the cards and.... I never got into water cooling. Do the Hydro Copper 780ti/TX allow those QDC things? Doesn't specifically say.
As I said above, I wouldn't use just a 360 for a pair of gpu's and the cpu. I would want at least another 120/140mm rad for that. QDC's don't connect to blocks/pumps/rads. They connect to other QDC's. For pumps/rads/blocks (including the hydro copper) you need compression fittings or barbs.