It is for sure that both systems are capable of steering your boat. Both systems have nearly the same linkage so may give the same steering performance. The differences between the systems are the following. Aries has ball bearings, which is a definite advantage in light winds, as it responds better. Also the pendulum area is a bit bigger on the Aries. I suppose your boat has a long keel and an unbalanced rudder, so some more steering power from the Aries could be helpful.
I also suppose the Aries is easier to install at the stern.
The Aries has a limited travel on the pendulum, which is claimed to be an advantage in extreme situations. The Windpilot pendulum can be turned out of the water in an easy way, when not in use.
For serious blue water tracks I should go for the Aries.