I would have opted for a considerably bigger radiator outside the case, the wall mounted type normally used for heating rooms.
No fans needed for it, so it's quieter than the triple rad. With enough water (10+ litres in the system) it's futile to wait for the temperature to peak since it will take many hours.(1)
There are a few advantages with water cooling. Each being more or less relevant depending on circumstances:
- Cooling (transfer of heat to the surrounding air) can be done where there's room for it, not necessarily at the hot spot.
- Case size doesn't limit the size of the radiator, if it's placed outside the case.
- Thermal inertia. As noted on page 9 of the article the temperature change is slow, which prevents the thermal fatigue associated with heatpipe coolers. (Your CPU/GPU can survive for decades rather than years.)(2)
(1) With 25 litres of water, starting at +20C, and NO radiator the tested rig could easily be running for one and a half hours at full test load without going anywhere near "hot" (the water only reaching +40C).
(2) Thermal fatigue of course isn't a problem for a system running 24/7 at near constant load, occupied with bitcoin mining or distributed computing and such.