Targa's will be fine. They are somewhat stiff, but nothing you cannot get used to pretty quickly. If you are grabbing a board through the pro deal then the Anthem is going to be closest to the Burton Custom.
The Anthem is definitely stiffer than the Custom is now to the point where they are are not comparable. A more comparable board to the Custom is probably the Agent. The Custom has gotten softer over the years as people have migrated to softer freestyle/park boards while the Anthem is probably closer to what the Custom used to be when Rome was first created.