Dave,
The answer to your question is simple - get a Shift. T-Road Pearl, Pyro, and Double Agent are all great balls but IMO the Shift was designed to replace the Ace.
The Double Agent is a great control medium-heavy oil ball, but the roll is very different and it starts up early in the midlane as compared to the late midlane roll of the Ace.
T-Road is a nasty (in a good way) late moving ball - but it is 100% a backend ball that will not give you similar traction as the Ace.
Pyro is the closest of the rest of the list, but it is a bit weaker than the
Ace and does not have quite the angle you can get out of an asymetric pearl particle.
Go with the Shift - you will not be disappointed. Basically it is the Ace with a stronger move to the pocket.
