You will benefit from using a fly line made for the European methods. While your weight forward or double taper line may suffice, it will tend to sag between guides, resulting in a loss of contact with your flies. This is due to the heavier taper of a standard line. Lines made for the European methods have little to no taper, a thin diameter and usually a braided core. A thin, minimally tapered, line is lightweight and does not sag or pull back toward the reel, allowing you to stay in contact with your flies. The braided core helps with low memory and allows the leader to be spliced into if for a seamless connection.