I recall seeing a rally cross car with a valve to limit but not completely block the fluid movement used I believe more as a damper. The standard car rolled to around 3 degrees at 0.6G from memory which is pretty much flat and about as hard cornering as you would normally experience on public roads before tyre squeal attracted the local constabulary's attention. However with wide tyres on a race track it might be different but I am still surprised that it was "incredible".
If I understand Aaron properly, the displacers were initially set up independent of each other and not linked front to rear. I suppose that fluid would give the ride height, but there couldn't have been much "spring" if the fluid couldn't move. I was curious that Aaron felt the car rolled badly when connected properly. Mine rides pretty much flat when driven spiritedly.
In theory disconnecting the units will not change roll angles much, in practice the higher weight on the front will allow for a little additional roll with interconnection, in particular under braking. But the separated units will see much higher pressure peaks than interconnected ones - this will be highlighted if the front units are somewhat worn out and stiffer than they should be. It would seem safer to reduce the ride height by 1-2 cm just by having less static pressure in the system.