I'm missing something here. What's the drawback with taper crimped rounds when using a speedloader?
If you are a competitive shooter you are probably shooting an 8 shot revolver (but same applies to a 6 shot). Trying to do a quick reload with taper crimp rounds is very slow because the edges of the rounds catch the cylinder and you have to wiggle the moon clip or speed loader to get the rounds in. Unless you do major throating to the ejector and cylinder the rounds usually will not just drop into the cylinder like roll crimped rounds will.