I've only sold one Drake with the new Eco-Flush and have not had feedback yet on it's flush.
The Drake and the Nexus both have the G-max flush and i believe the only difference i can see on the Eco is the fill valve has been changed and the flapper now has a float attached to the top of it which would make it close faster.
This would limit the amout of water leaving the tank using less water.
I would think if there was not a great flush you could remove the extra float in essence letting more water into the bowl and giving it a stronger flush.
I have had the Caroma Caravelle installed before in our showroom bathroom and we had lots of problem with marking.
The Caroma Sydney comfort height round 270 bowl