RE:What is LC-13 line?
whoops! I didn't read your question right... the diff between T-series and depth charge (Orvis) and 444 QD and .... others is "not much". I am not knowledgeable about the Orvis but own the other two + SA STS taper heads. They are based on the same principle, impregnated flyline coating in a dense short head attached to skinny shooting line with good characteristics. The price is pretty consistent too.
LC-13 on the other hand is really cheap.