I put elec rudder trim on my Super 8 mainly due to the 2 cruise speeds I fly. 4 banger speeds with my buds, and Super 8 speeds alone. When I had my metal prop, I used this quite a bit. And only in the 2 cruise configurations. Since I have gone to the Hartzell composite, I dont use it at all, even though Im flying the 2 cruise speeds still.
My advice, Unless you intend to cruise at 2 different speeds that span >25kts, elec trim is of no use and a single fixed trim tab is all that is necessary. Elec trim is of even less use if you use a light weight prop.