Yeah, the depth charge is a good example. The head does sink fast, and the running line much less so which (to me anyway) gives you a as close to a diagonal line from your rowboat to the fly. Other companies have similar lines, usually identified as "integrated fast-sink shooting heads" since there isn't a loop-loop connection.
My experience with regular "full sinking" lines is that they do get down, but the belly of the line tends to sink as much or more than the "head" making strikes a lot harder to detect.
The depth charge type lines are more expensive, but well-worth it IMO.
I'm still not great at casting them, but you really don't have to cast them very far to catch all of the shad you want. I usually just flop them to one side, and then water haul over to make the cast.
Gene